*** a/src/backend/tsearch/spell.c
--- b/src/backend/tsearch/spell.c
***************
*** 429,443 **** NIAddAffix(IspellDict *Conf, int flag, char flagflags, const char *mask, const c
  		err = pg_regcomp(&(Affix->reg.regex), wmask, wmasklen,
  						 REG_ADVANCED | REG_NOSUB,
  						 DEFAULT_COLLATION_OID);
  		if (err)
! 		{
! 			char		errstr[100];
! 
! 			pg_regerror(err, &(Affix->reg.regex), errstr, sizeof(errstr));
! 			ereport(ERROR,
! 					(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
! 					 errmsg("invalid regular expression: %s", errstr)));
! 		}
  	}
  
  	Affix->flagflags = flagflags;
--- 429,437 ----
  		err = pg_regcomp(&(Affix->reg.regex), wmask, wmasklen,
  						 REG_ADVANCED | REG_NOSUB,
  						 DEFAULT_COLLATION_OID);
+ 		/* Ignore regular expression error and do not add wrong affix */
  		if (err)
! 			return;
  	}
  
  	Affix->flagflags = flagflags;