diff --git a/plugins/ActivityPub/actions/apinbox.php b/plugins/ActivityPub/actions/apinbox.php
index e7f8663b9d..04c4341e5e 100644
--- a/plugins/ActivityPub/actions/apinbox.php
+++ b/plugins/ActivityPub/actions/apinbox.php
@@ -37,7 +37,7 @@ defined('GNUSOCIAL') || die();
 class apInboxAction extends ManagedAction
 {
     protected $needLogin = false;
-    protected $canPost   = true;
+    protected $canPost = true;
 
     /**
      * Handle the Inbox request
@@ -57,15 +57,33 @@ class apInboxAction extends ManagedAction
 
         common_debug('ActivityPub Inbox: Received a POST request.');
         $body = $data = file_get_contents('php://input');
-        common_debug('ActivityPub Inbox: Request contents: '.$data);
+        common_debug('ActivityPub Inbox: Request contents: ' . $data);
         $data = json_decode(file_get_contents('php://input'), true);
 
         if (!isset($data['actor'])) {
             ActivityPubReturn::error('Actor not found in the request.');
         }
 
-        $actor = Activitypub_explorer::get_profile_from_url($data['actor']);
-        $aprofile = Activitypub_profile::from_profile($actor);
+        try {
+            $actor = Activitypub_explorer::get_profile_from_url($data['actor']);
+        } catch (HTTP_Request2_Exception $e) {
+            ActivityPubReturn::error('Failed to retrieve remote actor information.');
+        } catch (NoProfileException $e) {
+            // Assert: This won't happen.
+            common_log(LOG_ERR, 'PLEASE REPORT THIS: ActivityPub Inbox Handler failed with NoProfileException while retrieving remote actor information: ' . $e->getMessage());
+            ActivityPubReturn::error('An unknown error has occurred. This was logged, please alert the sysadmin.');
+        } catch (ServerException $e) {
+            ActivityPubReturn::error('Could not store this remote actor.');
+        } catch (Exception $e) {
+            ActivityPubReturn::error('Invalid actor.');
+        }
+        try {
+            $aprofile = Activitypub_profile::from_profile($actor);
+        } catch (Exception $e) {
+            // Assert: This won't happen.
+            common_log(LOG_ERR, 'PLEASE REPORT THIS: ActivityPub Inbox Handler failed while retrieving AProfile from Profile: ' . $e->getMessage());
+            ActivityPubReturn::error('An unknown error has occurred. This was logged, please alert the sysadmin.');
+        }
 
         $actor_public_key = new Activitypub_rsa();
         $actor_public_key = $actor_public_key->ensure_public_key($actor);
@@ -73,7 +91,7 @@ class apInboxAction extends ManagedAction
         common_debug('ActivityPub Inbox: HTTP Signature: Validation will now start!');
 
         $headers = $this->get_all_headers();
-        common_debug('ActivityPub Inbox: Request Headers: '.print_r($headers, true));
+        common_debug('ActivityPub Inbox: Request Headers: ' . print_r($headers, true));
 
         if (!isset($headers['signature'])) {
             common_debug('ActivityPub Inbox: HTTP Signature: Missing Signature header.');
@@ -82,25 +100,33 @@ class apInboxAction extends ManagedAction
 
         // Extract the signature properties
         $signatureData = HTTPSignature::parseSignatureHeader($headers['signature']);
-        common_debug('ActivityPub Inbox: HTTP Signature Data: '.print_r($signatureData, true));
+        common_debug('ActivityPub Inbox: HTTP Signature Data: ' . print_r($signatureData, true));
         if (isset($signatureData['error'])) {
-            common_debug('ActivityPub Inbox: HTTP Signature: '.json_encode($signatureData, true));
+            common_debug('ActivityPub Inbox: HTTP Signature: ' . json_encode($signatureData, true));
             ActivityPubReturn::error(json_encode($signatureData, true), 400);
         }
 
         list($verified, $headers) = HTTPSignature::verify($actor_public_key, $signatureData, $headers, $path, $body);
 
-        // If the signature fails verification the first time, update profile as it might have change public key
-        if($verified !== 1) {
-            $res = Activitypub_explorer::get_remote_user_activity($aprofile->getUri());
-            $actor = Activitypub_profile::update_profile($aprofile, $res);
+        // If the signature fails verification the first time, update profile as it might have changed public key
+        if ($verified !== 1) {
+            try {
+                $res = Activitypub_explorer::get_remote_user_activity($aprofile->getUri());
+            } catch (Exception $e) {
+                ActivityPubReturn::error('Invalid remote actor.');
+            }
+            try {
+                $actor = Activitypub_profile::update_profile($aprofile, $res);
+            } catch (Exception $e) {
+                ActivityPubReturn::error('Failed to updated remote actor information.');
+            }
             $actor_public_key = new Activitypub_rsa();
             $actor_public_key = $actor_public_key->ensure_public_key($actor);
-            list($verified, $headers) = HTTPSignature::verify($actor_public_key, $signatureData, $headers, $path, $body);
+            list($verified, /*$headers*/) = HTTPSignature::verify($actor_public_key, $signatureData, $headers, $path, $body);
         }
 
         // If it still failed despite profile update
-        if($verified !== 1) {
+        if ($verified !== 1) {
             common_debug('ActivityPub Inbox: HTTP Signature: Invalid signature.');
             ActivityPubReturn::error('Invalid signature.');
         }
diff --git a/plugins/ActivityPub/classes/Activitypub_profile.php b/plugins/ActivityPub/classes/Activitypub_profile.php
index 61c77f5e2b..b73d4bc131 100644
--- a/plugins/ActivityPub/classes/Activitypub_profile.php
+++ b/plugins/ActivityPub/classes/Activitypub_profile.php
@@ -53,8 +53,8 @@ class Activitypub_profile extends Managed_DataObject
     /**
      * Return table definition for Schema setup and DB_DataObject usage.
      *
-     * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @return array array of column definitions
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public static function schemaDef()
     {
@@ -81,6 +81,7 @@ class Activitypub_profile extends Managed_DataObject
      * @return array array to be used in a response
      * @throws InvalidUrlException
      * @throws ServerException
+     * @throws Exception
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public static function profile_to_array($profile)
@@ -91,38 +92,38 @@ class Activitypub_profile extends Managed_DataObject
         $public_key = $rsa->ensure_public_key($profile);
         unset($rsa);
         $res = [
-            '@context'          => [
+            '@context' => [
                 'https://www.w3.org/ns/activitystreams',
                 'https://w3id.org/security/v1',
                 [
                     'manuallyApprovesFollowers' => 'as:manuallyApprovesFollowers'
                 ]
             ],
-            'id'                => $uri,
-            'type'              => 'Person',
-            'following'         => common_local_url('apActorFollowing', ['id' => $id]),
-            'followers'         => common_local_url('apActorFollowers', ['id' => $id]),
-            'liked'             => common_local_url('apActorLiked', ['id' => $id]),
-            'inbox'             => common_local_url('apInbox', ['id' => $id]),
-            'outbox'            => common_local_url('apActorOutbox', ['id' => $id]),
+            'id' => $uri,
+            'type' => 'Person',
+            'following' => common_local_url('apActorFollowing', ['id' => $id]),
+            'followers' => common_local_url('apActorFollowers', ['id' => $id]),
+            'liked' => common_local_url('apActorLiked', ['id' => $id]),
+            'inbox' => common_local_url('apInbox', ['id' => $id]),
+            'outbox' => common_local_url('apActorOutbox', ['id' => $id]),
             'preferredUsername' => $profile->getNickname(),
-            'name'              => $profile->getBestName(),
-            'summary'           => ($desc = $profile->getDescription()) == null ? "" : $desc,
-            'url'               => $profile->getUrl(),
+            'name' => $profile->getBestName(),
+            'summary' => ($desc = $profile->getDescription()) == null ? "" : $desc,
+            'url' => $profile->getUrl(),
             'manuallyApprovesFollowers' => false,
             'publicKey' => [
-                'id'    => $uri."#public-key",
+                'id' => $uri . "#public-key",
                 'owner' => $uri,
                 'publicKeyPem' => $public_key
             ],
             'tag' => [],
             'attachment' => [],
             'icon' => [
-                'type'      => 'Image',
+                'type' => 'Image',
                 'mediaType' => 'image/png',
-                'height'    => AVATAR_PROFILE_SIZE,
-                'width'     => AVATAR_PROFILE_SIZE,
-                'url'       => $profile->avatarUrl(AVATAR_PROFILE_SIZE)
+                'height' => AVATAR_PROFILE_SIZE,
+                'width' => AVATAR_PROFILE_SIZE,
+                'url' => $profile->avatarUrl(AVATAR_PROFILE_SIZE)
             ]
         ];
 
@@ -140,9 +141,9 @@ class Activitypub_profile extends Managed_DataObject
     /**
      * Insert the current object variables into the database
      *
+     * @throws ServerException
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @access public
-     * @throws ServerException
      */
     public function do_insert()
     {
@@ -151,11 +152,11 @@ class Activitypub_profile extends Managed_DataObject
         $profile->created = $this->created = $this->modified = common_sql_now();
 
         $fields = [
-                    'uri'      => 'profileurl',
-                    'nickname' => 'nickname',
-                    'fullname' => 'fullname',
-                    'bio'      => 'bio'
-                    ];
+            'uri' => 'profileurl',
+            'nickname' => 'nickname',
+            'fullname' => 'fullname',
+            'bio' => 'bio'
+        ];
 
         foreach ($fields as $af => $pf) {
             $profile->$pf = $this->$af;
@@ -179,7 +180,7 @@ class Activitypub_profile extends Managed_DataObject
     /**
      * Fetch the locally stored profile for this Activitypub_profile
      *
-     * @return Profile
+     * @return get_called_class
      * @throws NoProfileException if it was not found
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
@@ -195,10 +196,10 @@ class Activitypub_profile extends Managed_DataObject
     /**
      * Generates an Activitypub_profile from a Profile
      *
-     * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @param Profile $profile
      * @return Activitypub_profile
      * @throws Exception if no Activitypub_profile exists for given Profile
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public static function from_profile(Profile $profile)
     {
@@ -211,16 +212,16 @@ class Activitypub_profile extends Managed_DataObject
                 // create one!
                 $aprofile = self::create_from_local_profile($profile);
             } else {
-                throw new Exception('No Activitypub_profile for Profile ID: '.$profile_id. ', this is a local user.');
+                throw new Exception('No Activitypub_profile for Profile ID: ' . $profile_id . ', this is a local user.');
             }
         }
 
         $fields = [
-                    'uri'      => 'profileurl',
-                    'nickname' => 'nickname',
-                    'fullname' => 'fullname',
-                    'bio'      => 'bio'
-                    ];
+            'uri' => 'profileurl',
+            'nickname' => 'nickname',
+            'fullname' => 'fullname',
+            'bio' => 'bio'
+        ];
 
         foreach ($fields as $af => $pf) {
             $aprofile->$af = $profile->$pf;
@@ -229,7 +230,8 @@ class Activitypub_profile extends Managed_DataObject
         return $aprofile;
     }
 
-    public static function from_profile_collection(array $profiles): array {
+    public static function from_profile_collection(array $profiles): array
+    {
         $ap_profiles = [];
 
         foreach ($profiles as $profile) {
@@ -251,6 +253,8 @@ class Activitypub_profile extends Managed_DataObject
      * @param Profile $profile
      * @return Activitypub_profile
      * @throws HTTP_Request2_Exception
+     * @throws Exception
+     * @throws Exception
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     private static function create_from_local_profile(Profile $profile)
@@ -266,13 +270,13 @@ class Activitypub_profile extends Managed_DataObject
 
         $aprofile->created = $aprofile->modified = common_sql_now();
 
-        $aprofile                 = new Activitypub_profile;
-        $aprofile->profile_id     = $profile->getID();
-        $aprofile->uri            = $url;
-        $aprofile->nickname       = $profile->getNickname();
-        $aprofile->fullname       = $profile->getFullname();
-        $aprofile->bio            = substr($profile->getDescription(), 0, 1000);
-        $aprofile->inboxuri       = $inboxes["inbox"];
+        $aprofile = new Activitypub_profile;
+        $aprofile->profile_id = $profile->getID();
+        $aprofile->uri = $url;
+        $aprofile->nickname = $profile->getNickname();
+        $aprofile->fullname = $profile->getFullname();
+        $aprofile->bio = substr($profile->getDescription(), 0, 1000);
+        $aprofile->inboxuri = $inboxes["inbox"];
         $aprofile->sharedInboxuri = $inboxes["sharedInbox"];
 
         $aprofile->insert();
@@ -283,8 +287,8 @@ class Activitypub_profile extends Managed_DataObject
     /**
      * Returns sharedInbox if possible, inbox otherwise
      *
-     * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @return string Inbox URL
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public function get_inbox()
     {
@@ -298,8 +302,8 @@ class Activitypub_profile extends Managed_DataObject
     /**
      * Getter for uri property
      *
-     * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @return string URI
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public function getUri()
     {
@@ -309,8 +313,8 @@ class Activitypub_profile extends Managed_DataObject
     /**
      * Getter for url property
      *
-     * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @return string URL
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public function getUrl()
     {
@@ -320,8 +324,8 @@ class Activitypub_profile extends Managed_DataObject
     /**
      * Getter for id property
      *
-     * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @return int
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public function getID()
     {
@@ -352,11 +356,11 @@ class Activitypub_profile extends Managed_DataObject
      * This should never return null -- you will either get an object or
      * an exception will be thrown.
      *
-     * @author GNU social
-     * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @param string $addr WebFinger address
      * @return Activitypub_profile
      * @throws Exception on error conditions
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @author GNU social
      */
     public static function ensure_webfinger($addr)
     {
@@ -402,7 +406,7 @@ class Activitypub_profile extends Managed_DataObject
         // If there's an Hcard, let's grab its info
         if (array_key_exists('hcard', $hints)) {
             if (!array_key_exists('profileurl', $hints) ||
-                        $hints['hcard'] != $hints['profileurl']) {
+                $hints['hcard'] != $hints['profileurl']) {
                 $hcardHints = DiscoveryHints::fromHcardUrl($hints['hcard']);
                 $hints = array_merge($hcardHints, $hints);
             }
@@ -441,17 +445,17 @@ class Activitypub_profile extends Managed_DataObject
      * @param Activitypub_profile $aprofile
      * @param array $res remote response
      * @return Profile remote Profile object
-     * @throws Exception
+     * @throws NoProfileException
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public static function update_profile($aprofile, $res)
     {
         // ActivityPub Profile
-        $aprofile->uri            = $res['id'];
-        $aprofile->nickname       = $res['preferredUsername'];
-        $aprofile->fullname       = isset($res['name']) ? $res['name'] : null;
-        $aprofile->bio            = isset($res['summary']) ? substr(strip_tags($res['summary']), 0, 1000) : null;
-        $aprofile->inboxuri       = $res['inbox'];
+        $aprofile->uri = $res['id'];
+        $aprofile->nickname = $res['preferredUsername'];
+        $aprofile->fullname = isset($res['name']) ? $res['name'] : null;
+        $aprofile->bio = isset($res['summary']) ? substr(strip_tags($res['summary']), 0, 1000) : null;
+        $aprofile->inboxuri = $res['inbox'];
         $aprofile->sharedInboxuri = isset($res['endpoints']['sharedInbox']) ? $res['endpoints']['sharedInbox'] : $res['inbox'];
 
         $profile = $aprofile->local_profile();
@@ -459,11 +463,11 @@ class Activitypub_profile extends Managed_DataObject
         $profile->modified = $aprofile->modified = common_sql_now();
 
         $fields = [
-                    'uri'      => 'profileurl',
-                    'nickname' => 'nickname',
-                    'fullname' => 'fullname',
-                    'bio'      => 'bio'
-                    ];
+            'uri' => 'profileurl',
+            'nickname' => 'nickname',
+            'fullname' => 'fullname',
+            'bio' => 'bio'
+        ];
 
         foreach ($fields as $af => $pf) {
             $profile->$pf = $aprofile->$af;
@@ -482,7 +486,7 @@ class Activitypub_profile extends Managed_DataObject
                 Activitypub_explorer::update_avatar($profile, $res['icon']['url']);
             } catch (Exception $e) {
                 // Let the exception go, it isn't a serious issue
-                common_debug('An error ocurred while grabbing remote avatar'.$e->getMessage());
+                common_debug('An error ocurred while grabbing remote avatar' . $e->getMessage());
             }
         }
 
@@ -497,7 +501,8 @@ class Activitypub_profile extends Managed_DataObject
      * @return int number of subscribers
      * @author Bruno Casteleiro <brunoccast@fc.up.pt>
      */
-    public static function subscriberCount(Profile $profile): int {
+    public static function subscriberCount(Profile $profile): int
+    {
         $cnt = self::cacheGet(sprintf('activitypub_profile:subscriberCount:%d', $profile->id));
 
         if ($cnt !== false && is_int($cnt)) {
@@ -523,7 +528,8 @@ class Activitypub_profile extends Managed_DataObject
      * @return int number of subscriptions
      * @author Bruno Casteleiro <brunoccast@fc.up.pt>
      */
-    public static function subscriptionCount(Profile $profile): int {
+    public static function subscriptionCount(Profile $profile): int
+    {
         $cnt = self::cacheGet(sprintf('activitypub_profile:subscriptionCount:%d', $profile->id));
 
         if ($cnt !== false && is_int($cnt)) {
@@ -541,19 +547,21 @@ class Activitypub_profile extends Managed_DataObject
         return $cnt;
     }
 
-    public static function updateSubscriberCount(Profile $profile, $adder) {
+    public static function updateSubscriberCount(Profile $profile, $adder)
+    {
         $cnt = self::cacheGet(sprintf('activitypub_profile:subscriberCount:%d', $profile->id));
 
         if ($cnt !== false && is_int($cnt)) {
-            self::cacheSet(sprintf('activitypub_profile:subscriberCount:%d', $profile->id), $cnt+$adder);
+            self::cacheSet(sprintf('activitypub_profile:subscriberCount:%d', $profile->id), $cnt + $adder);
         }
     }
 
-    public static function updateSubscriptionCount(Profile $profile, $adder) {
+    public static function updateSubscriptionCount(Profile $profile, $adder)
+    {
         $cnt = self::cacheGet(sprintf('activitypub_profile:subscriptionCount:%d', $profile->id));
 
         if ($cnt !== false && is_int($cnt)) {
-            self::cacheSet(sprintf('activitypub_profile:subscriptionCount:%d', $profile->id), $cnt+$adder);
+            self::cacheSet(sprintf('activitypub_profile:subscriptionCount:%d', $profile->id), $cnt + $adder);
         }
     }
 
@@ -567,7 +575,8 @@ class Activitypub_profile extends Managed_DataObject
      * @return array subscriber profile objects
      * @author Bruno Casteleiro <brunoccast@fc.up.pt>
      */
-    public static function getSubscribers(Profile $profile, $offset = 0, $limit = null): array {
+    public static function getSubscribers(Profile $profile, $offset = 0, $limit = null): array
+    {
         $cache = false;
         if ($offset + $limit <= Subscription::CACHE_WINDOW) {
             $subs = self::cacheGet(sprintf('activitypub_profile:subscriberCollection:%d', $profile->id));
@@ -612,7 +621,8 @@ class Activitypub_profile extends Managed_DataObject
      * @return array subscribed profile objects
      * @author Bruno Casteleiro <brunoccast@fc.up.pt>
      */
-    public static function getSubscribed(Profile $profile, $offset = 0, $limit = null): array {
+    public static function getSubscribed(Profile $profile, $offset = 0, $limit = null): array
+    {
         $cache = false;
         if ($offset + $limit <= Subscription::CACHE_WINDOW) {
             $subs = self::cacheGet(sprintf('activitypub_profile:subscribedCollection:%d', $profile->id));
@@ -641,7 +651,7 @@ class Activitypub_profile extends Managed_DataObject
         }
 
         if ($cache) {
-           self::cacheSet(sprintf('activitypub_profile:subscribedCollection:%d', $profile->id), $profiles);
+            self::cacheSet(sprintf('activitypub_profile:subscribedCollection:%d', $profile->id), $profiles);
         }
 
         return $profiles;
@@ -654,9 +664,11 @@ class Activitypub_profile extends Managed_DataObject
      * @param Profile $actor subscriber profile object
      * @param Profile $other subscribed profile object
      * @return void
+     * @throws Exception
      * @author Bruno Casteleiro <brunoccast@fc.up.pt>
      */
-    public static function subscribeCacheUpdate(Profile $actor, Profile $other) {
+    public static function subscribeCacheUpdate(Profile $actor, Profile $other)
+    {
         self::blow('activitypub_profile:subscribedCollection:%d', $actor->getID());
         self::blow('activitypub_profile:subscriberCollection:%d', $other->id);
         self::updateSubscriptionCount($actor, +1);
@@ -670,9 +682,11 @@ class Activitypub_profile extends Managed_DataObject
      * @param Profile $actor subscriber profile object
      * @param Profile $other subscribed profile object
      * @return void
+     * @throws Exception
      * @author Bruno Casteleiro <brunoccast@fc.up.pt>
      */
-    public static function unsubscribeCacheUpdate(Profile $actor, Profile $other) {
+    public static function unsubscribeCacheUpdate(Profile $actor, Profile $other)
+    {
         self::blow('activitypub_profile:subscribedCollection:%d', $actor->getID());
         self::blow('activitypub_profile:subscriberCollection:%d', $other->id);
         self::updateSubscriptionCount($actor, -1);
diff --git a/plugins/ActivityPub/classes/Activitypub_rsa.php b/plugins/ActivityPub/classes/Activitypub_rsa.php
index b93ee23f3f..d9770dbb3b 100644
--- a/plugins/ActivityPub/classes/Activitypub_rsa.php
+++ b/plugins/ActivityPub/classes/Activitypub_rsa.php
@@ -46,27 +46,35 @@ class Activitypub_rsa extends Managed_DataObject
     /**
      * Return table definition for Schema setup and DB_DataObject usage.
      *
-     * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @return array array of column definitions
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public static function schemaDef()
     {
         return [
-                'fields' => [
-                    'profile_id'  => ['type' => 'int', 'not null' => true],
-                    'private_key' => ['type' => 'text'],
-                    'public_key'  => ['type' => 'text', 'not null' => true],
-                    'created' => ['type' => 'datetime', 'not null' => true, 'default' => 'CURRENT_TIMESTAMP', 'description' => 'date this record was created'],
-                    'modified' => ['type' => 'datetime', 'not null' => true, 'default' => 'CURRENT_TIMESTAMP', 'description' => 'date this record was modified'],
-                ],
-                'primary key' => ['profile_id'],
-                'foreign keys' => [
-                    'activitypub_profile_profile_id_fkey' => ['profile', ['profile_id' => 'id']],
-                ],
+            'fields' => [
+                'profile_id' => ['type' => 'int', 'not null' => true],
+                'private_key' => ['type' => 'text'],
+                'public_key' => ['type' => 'text', 'not null' => true],
+                'created' => ['type' => 'datetime', 'not null' => true, 'default' => 'CURRENT_TIMESTAMP', 'description' => 'date this record was created'],
+                'modified' => ['type' => 'datetime', 'not null' => true, 'default' => 'CURRENT_TIMESTAMP', 'description' => 'date this record was modified'],
+            ],
+            'primary key' => ['profile_id'],
+            'foreign keys' => [
+                'activitypub_profile_profile_id_fkey' => ['profile', ['profile_id' => 'id']],
+            ],
         ];
     }
 
-    public function get_private_key($profile)
+    /**
+     * Private key getter
+     *
+     * @param Profile $profile
+     * @return string
+     * @throws ServerException
+     * @throws Exception
+     */
+    public function get_private_key(Profile $profile): string
     {
         $this->profile_id = $profile->getID();
         $apRSA = self::getKV('profile_id', $this->profile_id);
@@ -90,9 +98,10 @@ class Activitypub_rsa extends Managed_DataObject
      * @param bool $fetch
      * @return string The public key
      * @throws ServerException It should never occur, but if so, we break everything!
+     * @throws Exception
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
-    public function ensure_public_key($profile, $fetch = true)
+    public function ensure_public_key(Profile $profile, bool $fetch = true): string
     {
         $this->profile_id = $profile->getID();
         $apRSA = self::getKV('profile_id', $this->profile_id);
@@ -119,11 +128,11 @@ class Activitypub_rsa extends Managed_DataObject
     /**
      * Insert the current object variables into the database.
      *
+     * @throws ServerException
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @access public
-     * @throws ServerException
      */
-    public function store_keys()
+    public function store_keys(): void
     {
         $this->created = $this->modified = common_sql_now();
         $ok = $this->insert();
@@ -135,14 +144,14 @@ class Activitypub_rsa extends Managed_DataObject
     /**
      * Generates a pair of RSA keys.
      *
-     * @author PHP Manual Contributed Notes <dirt@awoms.com>
      * @param string $private_key in/out
      * @param string $public_key in/out
+     * @author PHP Manual Contributed Notes <dirt@awoms.com>
      */
-    public static function generate_keys(&$private_key, &$public_key)
+    public static function generate_keys(string &$private_key, string &$public_key): void
     {
         $config = [
-            'digest_alg'       => 'sha512',
+            'digest_alg' => 'sha512',
             'private_key_bits' => 2048,
             'private_key_type' => OPENSSL_KEYTYPE_RSA,
         ];
@@ -162,12 +171,12 @@ class Activitypub_rsa extends Managed_DataObject
     /**
      * Update public key.
      *
-     * @param Profile $profile
+     * @param Profile|Activitypub_profile $profile
      * @param string $public_key
      * @throws Exception
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
-    public static function update_public_key($profile, $public_key)
+    public static function update_public_key($profile, string $public_key): void
     {
         // Public Key
         $apRSA = new Activitypub_rsa();
diff --git a/plugins/ActivityPub/lib/explorer.php b/plugins/ActivityPub/lib/explorer.php
index f4d2abee85..62ff446163 100644
--- a/plugins/ActivityPub/lib/explorer.php
+++ b/plugins/ActivityPub/lib/explorer.php
@@ -46,13 +46,13 @@ class Activitypub_explorer
     /**
      * Shortcut function to get a single profile from its URL.
      *
-     * @param  string $url
-     * @param  bool   $grab_online whether to try online grabbing, defaults to true
+     * @param string $url
+     * @param bool $grab_online whether to try online grabbing, defaults to true
      * @return Profile
-     * @throws HTTP_Request2_Exception
-     * @throws NoProfileException
-     * @throws Exception
-     * @throws ServerException
+     * @throws HTTP_Request2_Exception Network issues
+     * @throws NoProfileException This won't happen
+     * @throws Exception Invalid request
+     * @throws ServerException Error storing remote actor
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public static function get_profile_from_url($url, $grab_online = true)
@@ -71,8 +71,8 @@ class Activitypub_explorer
      * This function cleans the $this->discovered_actor_profiles array
      * so that there is no erroneous data
      *
-     * @param  string $url         User's url
-     * @param  bool   $grab_online whether to try online grabbing, defaults to true
+     * @param string $url User's url
+     * @param bool $grab_online whether to try online grabbing, defaults to true
      * @return array of Profile objects
      * @throws HTTP_Request2_Exception
      * @throws NoProfileException
@@ -97,8 +97,8 @@ class Activitypub_explorer
      * This is a recursive function that will accumulate the results on
      * $discovered_actor_profiles array
      *
-     * @param  string $url         User's url
-     * @param  bool   $grab_online whether to try online grabbing, defaults to true
+     * @param string $url User's url
+     * @param bool $grab_online whether to try online grabbing, defaults to true
      * @return array of Profile objects
      * @throws HTTP_Request2_Exception
      * @throws NoProfileException
@@ -122,7 +122,7 @@ class Activitypub_explorer
     /**
      * This ensures that we are using a valid ActivityPub URI
      *
-     * @param  string $url
+     * @param string $url
      * @return bool success state (related to the response)
      * @throws Exception (If the HTTP request fails)
      * @author Diogo Cordeiro <diogo@fc.up.pt>
@@ -146,8 +146,8 @@ class Activitypub_explorer
      * Get a local user profile from its URL and joins it on
      * $this->discovered_actor_profiles
      *
-     * @param  string $uri    Actor's uri
-     * @param  bool   $online
+     * @param string $uri Actor's uri
+     * @param bool $online
      * @return bool success state
      * @throws NoProfileException
      * @throws Exception
@@ -171,6 +171,7 @@ class Activitypub_explorer
         // Is this a known filthy little mudblood?
         $aprofile = self::get_aprofile_by_url($uri);
         if ($aprofile instanceof Activitypub_profile) {
+            // Assert: This AProfile has a Profile, no try catch.
             $profile = $aprofile->local_profile();
             common_debug('ActivityPub Explorer: Found a local Aprofile for ' . $uri);
             // We found something!
@@ -184,7 +185,7 @@ class Activitypub_explorer
             $ACTIVITYPUB_BASE_ACTOR_URI_length = strlen(ACTIVITYPUB_BASE_ACTOR_URI);
             if (substr($uri, 0, $ACTIVITYPUB_BASE_ACTOR_URI_length) == ACTIVITYPUB_BASE_ACTOR_URI) {
                 try {
-                    $profile = Profile::getByID(intval(substr($uri, $ACTIVITYPUB_BASE_ACTOR_URI_length)));
+                    $profile = Profile::getByID((int)substr($uri, $ACTIVITYPUB_BASE_ACTOR_URI_length));
                     common_debug('ActivityPub Explorer: Found a Profile for ' . $uri);
                     // We found something!
                     $this->discovered_actor_profiles[] = $profile;
@@ -210,7 +211,7 @@ class Activitypub_explorer
      * Get a remote user(s) profile(s) from its URL and joins it on
      * $this->discovered_actor_profiles
      *
-     * @param  string $url User's url
+     * @param string $url User's url
      * @return bool success state
      * @throws HTTP_Request2_Exception
      * @throws NoProfileException
@@ -247,7 +248,7 @@ class Activitypub_explorer
     /**
      * Save remote user profile in local instance
      *
-     * @param  array $res remote response
+     * @param array $res remote response
      * @return Profile remote Profile object
      * @throws NoProfileException
      * @throws ServerException
@@ -290,8 +291,8 @@ class Activitypub_explorer
     /**
      * Download and update given avatar image
      *
-     * @param  Profile $profile
-     * @param  string  $url
+     * @param Profile $profile
+     * @param string $url
      * @return Avatar    The Avatar we have on disk.
      * @throws Exception in various failure cases
      * @author GNU social
@@ -357,7 +358,7 @@ class Activitypub_explorer
      * Validates a remote response in order to determine whether this
      * response is a valid profile or not
      *
-     * @param  array $res remote response
+     * @param array $res remote response
      * @return bool success state
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
@@ -376,7 +377,7 @@ class Activitypub_explorer
      * potential ActivityPub remote profiles, as so it is important to use
      * this hacky workaround (at least for now)
      *
-     * @param  string $v URL
+     * @param string $v URL
      * @return bool|Activitypub_profile false if fails | Aprofile object if successful
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
@@ -399,7 +400,7 @@ class Activitypub_explorer
     /**
      * Given a valid actor profile url returns its inboxes
      *
-     * @param  string $url of Actor profile
+     * @param string $url of Actor profile
      * @return bool|array false if fails | array with inbox and shared inbox if successful
      * @throws HTTP_Request2_Exception
      * @throws Exception
@@ -426,7 +427,7 @@ class Activitypub_explorer
     /**
      * Allows the Explorer to transverse a collection of persons.
      *
-     * @param  string $url
+     * @param string $url
      * @return bool
      * @throws HTTP_Request2_Exception
      * @throws NoProfileException
@@ -461,9 +462,9 @@ class Activitypub_explorer
      * Get a remote user array from its URL (this function is only used for
      * profile updating and shall not be used for anything else)
      *
-     * @param  string $url User's url
-     * @return mixed
-     * @throws Exception
+     * @param string $url User's url
+     * @return array
+     * @throws Exception Either network issues or unsupported Activity format
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
     public static function get_remote_user_activity($url)