diff --git a/C/errors.c b/C/errors.c
index b53ec6c43..fd0411bd6 100755
--- a/C/errors.c
+++ b/C/errors.c
@@ -68,7 +68,24 @@ bool Yap_Warning(const char *s, ...) {
   rc = Yap_execute_pred(pred, ts, true PASS_REGS);
   return rc;
 }
-void Yap_InitError(yap_error_number e, Term t, const char *msg) {
+
+void Yap_InitError__(const char *file, const char *function, int lineno, yap_error_number e, Term t, ...) {
+  CACHE_REGS
+  va_list ap;
+  va_start(ap, t);
+  const char *fmt;
+  char tmpbuf[MAXPATHLEN];
+
+  fmt = va_arg(ap, char *);
+  if (fmt != NULL) {
+#if HAVE_VSNPRINTF
+    vsnprintf(tmpbuf, MAXPATHLEN - 1, fmt, ap);
+#else
+    (void)vsprintf(tmpbuf, fmt, ap);
+#endif
+  } else
+    return;
+  va_end(ap);
   if (LOCAL_ActiveError->status) {
     Yap_exit(1);
   }
@@ -76,10 +93,10 @@ void Yap_InitError(yap_error_number e, Term t, const char *msg) {
   LOCAL_ActiveError->errorFile = NULL;
   LOCAL_ActiveError->errorFunction = NULL;
   LOCAL_ActiveError->errorLine = 0;
-  if (msg) {
-    LOCAL_Error_Size = strlen(msg);
+  if (fmt) {
+    LOCAL_Error_Size = strlen(tmpbuf);
     LOCAL_ActiveError->errorMsg = malloc(LOCAL_Error_Size + 1);
-    strcpy(LOCAL_ActiveError->errorMsg, msg);
+    strcpy(LOCAL_ActiveError->errorMsg, tmpbuf);
   } else {
     LOCAL_Error_Size = 0;
   }
diff --git a/C/scanner.c b/C/scanner.c
index b247027f2..0f4f1accb 100755
--- a/C/scanner.c
+++ b/C/scanner.c
@@ -970,6 +970,10 @@ static Term get_num(int *chp, int *chbuffp, StreamDesc *st, int sign) {
       number_overflow();
     *sp++ = ch;
     ch = getchr(st);
+    if (!iswhexnumber(ch))  {
+      Yap_InitError(SYNTAX_ERROR, TermNil, "empty hexadecimal number 0x%C",ch)   ;
+      return 0;
+    }
     while (my_isxdigit(ch, 'F', 'f')) {
       Int oval = val;
       int chval =
@@ -982,16 +986,27 @@ static Term get_num(int *chp, int *chbuffp, StreamDesc *st, int sign) {
       if (oval != (val - chval) / 16) /* overflow */
         has_overflow = TRUE;
       ch = getchr(st);
+
     }
     *chp = ch;
   } else if (ch == 'o' && base == 0) {
-    might_be_float = FALSE;
+    might_be_float = false;
     base = 8;
     ch = getchr(st);
+      if (ch < '0' || ch > '7') {
+          Yap_InitError(SYNTAX_ERROR, TermNil, "empty octal number 0b%C", ch)   ;
+        return 0;
+      }
   } else if (ch == 'b' && base == 0) {
-    might_be_float = FALSE;
+    might_be_float = false;
     base = 2;
     ch = getchr(st);
+  if (ch < '0' || ch > '1') {
+                                          Yap_InitError(SYNTAX_ERROR, TermNil, "empty binary  0b%C", ch)   ;
+    return 0;
+                                      }
+
+
   } else {
     val = base;
     base = 10;
@@ -1011,7 +1026,7 @@ static Term get_num(int *chp, int *chbuffp, StreamDesc *st, int sign) {
     }
     val = val * base + ch - '0';
     if (val / base != oval || val - oval * base != ch - '0') /* overflow */
-      has_overflow = TRUE;
+      has_overflow = true;
     ch = getchr(st);
   }
   if (might_be_float && (ch == '.' || ch == 'e' || ch == 'E')) {
@@ -1162,8 +1177,7 @@ Term Yap_scan_num(StreamDesc *inp, bool error_on) {
 #endif
   if (LOCAL_ErrorMessage != NULL || ch != -1 || cherr) {
     Yap_clean_tokenizer(old_tr, NULL, NULL);
-    if (error_on)
-      Yap_Error(SYNTAX_ERROR, ARG2, "converting number");
+   Yap_InitError(SYNTAX_ERROR, ARG2, "while converting stream %d to number", inp-GLOBAL_Stream );
     return 0;
   }
   return out;
@@ -1472,7 +1486,7 @@ TokEntry *Yap_tokenizer(struct stream_desc *st, bool store_comments,
       cherr = 0;
       CHECK_SPACE();
       if ((t->TokInfo = get_num(&cha, &cherr, st, sign)) == 0L) {
-        if (p) {
+        if (t->TokInfo == 0) {
           p->Tok = eot_tok;
           t->TokInfo = TermError;
         }
diff --git a/C/text.c b/C/text.c
index 577a8f39e..2f64a815d 100644
--- a/C/text.c
+++ b/C/text.c
@@ -719,21 +719,23 @@ static size_t write_length(const unsigned char *s0, seq_tv_t *out USES_REGS) {
 static Term write_number(unsigned char *s, seq_tv_t *out,
                          bool error_on USES_REGS) {
   Term t;
-  yap_error_number erro = LOCAL_Error_TYPE;
-  int i = push_text_stack();
+    yap_error_descriptor_t new_error;
+    int i = push_text_stack();
+    Yap_pushErrorContext(&new_error);
   t = Yap_StringToNumberTerm((char *)s, &out->enc, error_on);
   pop_text_stack(i);
-  LOCAL_Error_TYPE = erro;
+    Yap_popErrorContext(true);
   return t;
 }
 
 static Term string_to_term(void *s, seq_tv_t *out USES_REGS) {
   Term o;
-  yap_error_number erro = LOCAL_Error_TYPE;
-  o = out->val.t = Yap_BufferToTerm(s, TermNil);
-  LOCAL_Error_TYPE = erro;
+    yap_error_descriptor_t new_error;
+    Yap_pushErrorContext(&new_error);
+    o = out->val.t = Yap_BufferToTerm(s, TermNil);
+    Yap_popErrorContext(true);
 
-  return o;
+    return o;
 }
 
 bool write_Text(unsigned char *inp, seq_tv_t *out USES_REGS) {
diff --git a/CXX/yapq.hh b/CXX/yapq.hh
index e3f203c8b..bf95657dc 100644
--- a/CXX/yapq.hh
+++ b/CXX/yapq.hh
@@ -38,12 +38,10 @@ class X_API YAPPredicate;
 class X_API YAPQuery : public YAPPredicate {
   bool q_open;
   int q_state;
-  yhandle_t q_g, q_handles;
+  yhandle_t  q_handles;
   struct yami *q_p, *q_cp;
-  sigjmp_buf q_env;
   int q_flags;
   YAP_dogoalinfo q_h;
-  YAPQuery *oq;
   YAPPairTerm names;
   YAPTerm goal;
   // temporaries
diff --git a/include/YapError.h b/include/YapError.h
index 0be7c227d..ada04ff9b 100644
--- a/include/YapError.h
+++ b/include/YapError.h
@@ -37,10 +37,12 @@
 
 #define MAX_ERROR_MSG_SIZE 1024
 
-struct yami *Yap_Error__(const char *file, const char *function, int lineno,
+extern void Yap_InitError__(const char *file, const char *function, int lineno, yap_error_number e, YAP_Term g, ...);
+
+extern struct yami *Yap_Error__(const char *file, const char *function, int lineno,
                          yap_error_number err, YAP_Term wheret, ...);
 
-void Yap_ThrowError__(const char *file, const char *function, int lineno,
+extern void Yap_ThrowError__(const char *file, const char *function, int lineno,
                       yap_error_number err, YAP_Term wheret, ...)
 #ifndef MSC_VER
     __attribute__((noreturn))
@@ -50,6 +52,9 @@ void Yap_ThrowError__(const char *file, const char *function, int lineno,
 #define Yap_NilError(id, ...)                                                  \
   Yap_Error__(__FILE__, __FUNCTION__, __LINE__, id, TermNil, __VA_ARGS__)
 
+#define Yap_InitError(id, ...)                                                  \
+  Yap_InitError__(__FILE__, __FUNCTION__, __LINE__, id, TermNil, __VA_ARGS__)
+
 #define Yap_Error(id, inp, ...)                                                \
   Yap_Error__(__FILE__, __FUNCTION__, __LINE__, id, inp, __VA_ARGS__)
 
diff --git a/os/YapIOConfig.h.cmake b/os/YapIOConfig.h.cmake
index 8501f670f..afda3b27f 100644
--- a/os/YapIOConfig.h.cmake
+++ b/os/YapIOConfig.h.cmake
@@ -1,3 +1,12 @@
+
+// play nice
+#ifndef HAVE_PYTHON
+#cmakedefine HAVE_PYTHON  ${HAVE_PYTHON}
+#endif
+#if HAVE_PYTHON
+#include <Python.h>
+#endif
+
 /* Define if you have libreadline */
 #ifndef HAVE_LIBREADLINE
 #cmakedefine HAVE_LIBREADLINE  ${HAVE_LIBREADLINE}
diff --git a/os/chartypes.c b/os/chartypes.c
index bb0d60d20..0fad877be 100644
--- a/os/chartypes.c
+++ b/os/chartypes.c
@@ -95,9 +95,7 @@ Term Yap_StringToNumberTerm(const char *s, encoding_t *encp, bool error_on) {
     s++;
 #endif
   t = Yap_scan_num(GLOBAL_Stream + sno, error_on);
-  if (LOCAL_Error_TYPE == SYNTAX_ERROR)
-    LOCAL_Error_TYPE = YAP_NO_ERROR;
-  Yap_CloseStream(sno);
+    Yap_CloseStream(sno);
   UNLOCK(GLOBAL_Stream[sno].streamlock);
   return t;
 }
diff --git a/os/readterm.c b/os/readterm.c
index e760c10c0..7aa7c9ce5 100644
--- a/os/readterm.c
+++ b/os/readterm.c
@@ -324,9 +324,9 @@ static Term syntax_error(TokEntry *errtok, int sno, Term cmod, Int newpos) {
   CELL *Hi = HR;
   TokEntry *tok = LOCAL_tokptr;
   Int cline = tok->TokLine;
-    Int startpos = tok->TokPos;
-    errtok = LOCAL_toktide;
-    Int errpos = errtok->TokPos;
+  Int startpos = tok->TokPos;
+  errtok = LOCAL_toktide;
+  Int errpos = errtok->TokPos;
   UInt diff = 0;
   startline = MkIntegerTerm(cline);
   endline = MkIntegerTerm(cline);
@@ -335,15 +335,15 @@ static Term syntax_error(TokEntry *errtok, int sno, Term cmod, Int newpos) {
   if (LOCAL_ErrorMessage)
     tm = MkStringTerm(LOCAL_ErrorMessage);
   else {
-      tm = MkStringTerm("syntax error");
+    tm = MkStringTerm("syntax error");
   }
   if (GLOBAL_Stream[sno].status & Seekable_Stream_f) {
     if (errpos && newpos >= 0) {
       char o[128 + 1];
       diff = errpos - startpos;
       if (diff > 128) {
-	diff = 128;
-	startpos = errpos - diff;
+        diff = 128;
+        startpos = errpos - diff;
       }
 #if HAVE_FTELLO
       Int curpos = ftello(GLOBAL_Stream[sno].file);
@@ -729,7 +729,7 @@ static bool complete_clause_processing(FEnv *fe, TokEntry *tokstart) {
   CACHE_REGS
   Term v_vp, v_vnames, v_comments, v_pos;
 
-  if (fe->t0 & fe->t && !Yap_unify(fe->t, fe->t0))
+  if (fe->t0 && fe->t && !Yap_unify(fe->t, fe->t0))
     return false;
   if (fe->t && fe->vp)
     v_vp = get_variables(fe, tokstart);
@@ -907,6 +907,9 @@ static parser_state_t scanError(REnv *re, FEnv *fe, int inp_stream) {
     }
   }
   // go back to the start
+  if (LOCAL_Error_TYPE == SYNTAX_ERROR) {
+    return YAP_PARSING_ERROR;
+  }
   if (re->seekable) {
     if (GLOBAL_Stream[inp_stream].status & InMemory_Stream_f) {
       GLOBAL_Stream[inp_stream].u.mem_string.pos = re->cpos;
diff --git a/pl/boot.yap b/pl/boot.yap
index 3d093a5c2..861ceda6a 100644
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -107,7 +107,66 @@ private(_).
 :- use_system_module( '$_strict_iso', ['$check_iso_strict_clause'/1,
         '$iso_check_goal'/2]).
 
-% be careful here not to generate an undefined exception.
+% be careful here not to generate an undefined exception..
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 print_message(L,E) :-
 	'$number_of_clauses'(print_message(L,E), prolog_complete, 1),
diff --git a/pl/meta.yap b/pl/meta.yap
index 380969f00..9d7b0396b 100644
--- a/pl/meta.yap
+++ b/pl/meta.yap
@@ -300,8 +300,9 @@ meta_predicate declaration
     nonvar(G),
     G = (A = B),
     !.
-'$expand_goals'(\+A,\+A1,('$current_choice_point'(CP),AO,'$$cut_by'(CP)-> false;true),HM,SM,BM,HVars) :- !,
-	'$expand_goals'(A,A1,AO,HM,SM,BM,HVars).
+'$expand_goals'(\+A,\+A1,(AO-> false;true),HM,SM,BM,HVars) :- !,
+	'$expand_goals'(A,A1,AOO,HM,SM,BM,HVars),
+	'$clean_cuts'(AOO, AO).
 '$expand_goals'(once(A),once(A1),
 	('$current_choice_point'(CP),AO,'$$cut_by'(CP)),HM,SM,BM,HVars) :- !,
 	'$expand_goals'(A,A1,AO0,HM,SM,BM,HVars),