diff --git a/classes/File.php b/classes/File.php
index ba8cea9d96..18ad828925 100644
--- a/classes/File.php
+++ b/classes/File.php
@@ -139,7 +139,8 @@ class File extends Memcached_DataObject
                     $redir_url = $redir_data;
                     $redir_data = array();
                 } else {
-                    throw new ServerException("Can't process url '$given_url'");
+                    // TRANS: Server exception thrown when a URL cannot be processed.
+                    throw new ServerException(_("Cannot process URL '$given_url'"));
                 }
                 // TODO: max field length
                 if ($redir_url === $given_url || strlen($redir_url) > 255 || !$followRedirects) {
@@ -169,7 +170,9 @@ class File extends Memcached_DataObject
         if (empty($x)) {
             $x = File::staticGet($file_id);
             if (empty($x)) {
-                throw new ServerException("Robin thinks something is impossible.");
+                // FIXME: This could possibly be a clearer message :)
+                // TRANS: Server exception thrown when... Robin thinks something is impossible!
+                throw new ServerException(_("Robin thinks something is impossible."));
             }
         }
 
@@ -182,6 +185,8 @@ class File extends Memcached_DataObject
     function isRespectsQuota($user,$fileSize) {
 
         if ($fileSize > common_config('attachments', 'file_quota')) {
+            // TRANS: Message given if an upload is larger than the configured maximum.
+            // TRANS: %1$d is the byte limit for uploads, %2$d is the byte count for the uploaded file.
             return sprintf(_('No file may be larger than %1$d bytes ' .
                              'and the file you sent was %2$d bytes. Try to upload a smaller version.'),
                            common_config('attachments', 'file_quota'), $fileSize);
@@ -192,6 +197,8 @@ class File extends Memcached_DataObject
         $this->fetch();
         $total = $this->total + $fileSize;
         if ($total > common_config('attachments', 'user_quota')) {
+            // TRANS: Message given if an upload would exceed user quota.
+            // TRANS: %d (number) is the user quota in bytes.
             return sprintf(_('A file this large would exceed your user quota of %d bytes.'), common_config('attachments', 'user_quota'));
         }
         $query .= ' AND EXTRACT(month FROM file.modified) = EXTRACT(month FROM now()) and EXTRACT(year FROM file.modified) = EXTRACT(year FROM now())';
@@ -199,6 +206,8 @@ class File extends Memcached_DataObject
         $this->fetch();
         $total = $this->total + $fileSize;
         if ($total > common_config('attachments', 'monthly_quota')) {
+            // TRANS: Message given id an upload would exceed a user's monthly quota.
+            // TRANS: $d (number) is the monthly user quota in bytes.
             return sprintf(_('A file this large would exceed your monthly quota of %d bytes.'), common_config('attachments', 'monthly_quota'));
         }
         return true;
@@ -235,7 +244,8 @@ class File extends Memcached_DataObject
     static function path($filename)
     {
         if (!self::validFilename($filename)) {
-            throw new ClientException("Invalid filename");
+            // TRANS: Client exception thrown if a file upload does not have a valid name.
+            throw new ClientException(_("Invalid filename."));
         }
         $dir = common_config('attachments', 'dir');
 
@@ -249,7 +259,8 @@ class File extends Memcached_DataObject
     static function url($filename)
     {
         if (!self::validFilename($filename)) {
-            throw new ClientException("Invalid filename");
+            // TRANS: Client exception thrown if a file upload does not have a valid name.
+            throw new ClientException(_("Invalid filename."));
         }
         if(common_config('site','private')) {
 
@@ -342,4 +353,3 @@ class File extends Memcached_DataObject
         return !empty($enclosure);
     }
 }
-
diff --git a/classes/Group_member.php b/classes/Group_member.php
index 7b1760f767..2239461beb 100644
--- a/classes/Group_member.php
+++ b/classes/Group_member.php
@@ -38,6 +38,7 @@ class Group_member extends Memcached_DataObject
 
         if (!$result) {
             common_log_db_error($member, 'INSERT', __FILE__);
+            // TRANS: Exception thrown when joining a group fails.
             throw new Exception(_("Group join failed."));
         }
 
@@ -50,6 +51,7 @@ class Group_member extends Memcached_DataObject
                                               'profile_id' => $profile_id));
 
         if (empty($member)) {
+            // TRANS: Exception thrown when trying to leave a group the user is not a member of.
             throw new Exception(_("Not part of group."));
         }
 
@@ -57,6 +59,7 @@ class Group_member extends Memcached_DataObject
 
         if (!$result) {
             common_log_db_error($member, 'INSERT', __FILE__);
+            // TRANS: Exception thrown when trying to leave a group fails.
             throw new Exception(_("Group leave failed."));
         }
 
diff --git a/classes/Local_group.php b/classes/Local_group.php
index 42312ec63c..ccd0125cf4 100644
--- a/classes/Local_group.php
+++ b/classes/Local_group.php
@@ -38,6 +38,7 @@ class Local_group extends Memcached_DataObject
             $this->encache();
         } else {
             common_log_db_error($local, 'UPDATE', __FILE__);
+            // TRANS: Server exception thrown when updating a local group fails.
             throw new ServerException(_('Could not update local group.'));
         }
 
diff --git a/classes/Login_token.php b/classes/Login_token.php
index 51dc61262e..20d5d9dbce 100644
--- a/classes/Login_token.php
+++ b/classes/Login_token.php
@@ -73,6 +73,8 @@ class Login_token extends Memcached_DataObject
 
         if (!$result) {
             common_log_db_error($login_token, 'INSERT', __FILE__);
+            // TRANS: Exception thrown when trying creating a login token failed.
+            // TRANS: %s is the user nickname for which token creation failed.
             throw new Exception(sprintf(_('Could not create login token for %s'),
                                                  $user->nickname));
         }