MQL4 error diagnosis

MQL4 error codes: official meanings and next checks

MQL4 error codes identify runtime and trade failures recorded in _LastError. First check whether the API returned its documented failure value, then capture GetLastError immediately. Use the code to choose a specific diagnostic path instead of applying one generic retry.

See where Pineify fits Review the code example

GetLastErrorPattern.mq4.mq4

#property strict

bool SelectTicket(const int ticket)
  {
   ResetLastError();
   bool selected = OrderSelect(ticket, SELECT_BY_TICKET);
   if(selected)
      return(true);

   int error_code = GetLastError();
   Print("OrderSelect failed. error=", error_code,
         " ticket=", ticket);
   return(false);
  }

void OnStart()
  {
   int ticket = -1;
   if(!SelectTicket(ticket))
      return;

   Print("Selected order ", OrderTicket());
  }

Runtime and compiler codes differ
Return values come before error state
GetLastError resets _LastError
Each failure class needs its own response

Trade and execution errors

These codes cover request prices, stops, volume, account state, quotes, order limits, permissions, and broker policy. Use the page for the returned number because the correct fix and retry rule differ.

Error 129: invalid price Error 130: invalid stops Error 131: invalid volume Error 132: market closed Error 133: trade disabled Error 134: not enough money Error 136: off quotes Error 138: requote Error 145: modify denied Error 146: trade context busy Error 148: too many orders Error 149: hedge prohibited

Runtime, array, and parameter errors

Runtime failures can stop calculations or indicate an invalid call. Preserve the failed API and arguments because the number alone may not identify the offending value.

Error 0: no error Error 1: no result Error 3: invalid trade parameters Error 4013: zero divide Error 4024: internal error Error 4029: invalid array Error 4051: invalid parameter Error 4060: function not allowed Error 4074: history memory Error 4107: invalid price parameter Error 4108: invalid ticket

Permission, chart, file, and network errors

These errors often depend on terminal settings, server policy, object lifecycle, the MT4 file sandbox, allowed URLs, or current connectivity. Source changes cannot override every external restriction.

Error 4109: trade not allowed Error 4112: server disabled EA trading Error 4200: object exists Error 4202: object missing Error 4211: chart not found Error 5002: wrong file name Error 5004: cannot open file Error 5020: file missing Error 5200: invalid URL Error 5203: request failed

Compiler code 112 is a different table

Official MQL4 compilation error 112 means a double quotation mark was omitted. The official runtime table assigns internal error to 4024, so do not interpret “internal error 112” without first identifying whether the message came from MetaEditor or runtime logging.

Error 112: compiler vs runtime meaning MQL4 compile error guide

Review the complete example

The helper resets stale state, tests the OrderSelect return value, captures the error once on failure, and logs the ticket with the code.

An error number is not enough to validate a fix. Keep the failed API, arguments, terminal build, broker state, and exact timestamp with the diagnosis.

GetLastErrorPattern.mq4.mq4

#property strict

bool SelectTicket(const int ticket)
  {
   ResetLastError();
   bool selected = OrderSelect(ticket, SELECT_BY_TICKET);
   if(selected)
      return(true);

   int error_code = GetLastError();
   Print("OrderSelect failed. error=", error_code,
         " ticket=", ticket);
   return(false);
  }

void OnStart()
  {
   int ticket = -1;
   if(!SelectTicket(ticket))
      return;

   Print("Selected order ", OrderTicket());
  }

Where Pineify fits

Move from the rule to editable MQL4 source

Pineify can generate or revise one self-contained .mq4 file with MQL4-specific reference context. Its independent static checker returns MetaEditor diagnostics so you can repair source issues before testing in your own MT4 environment.

Open MQL4 Coding Agent

Static diagnostics do not prove runtime behavior, backtest results, broker compatibility, or live-trading safety.

Pineify MQL4 Coding Agent with MQL4 selected and an editable MetaTrader 4 code artifact

A practical workflow

1
Identify the failing API
Confirm its documented failure return value before using an error code.
2
Capture the code immediately
Call GetLastError once at the failure point and keep the relevant arguments.
3
Open the matching guide
Use the official meaning to separate input, market, account, permission, runtime, and environment failures.
4
Retest the corrected cause
Compile and reproduce in the same terminal, broker, symbol, account, and market state.

Frequently asked questions

How do I read MQL4 error codes?

Check the failed API result, call GetLastError immediately, then map the number through the official runtime error table.

Does GetLastError clear the error?

Yes. It returns the current _LastError value and resets that stored value, so capture it once and keep it in a local variable.

Are compiler and runtime error numbers the same?

No. MQL4 publishes separate compiler and runtime tables. Always identify where the message came from.

Should all MQL4 errors be retried?

No. Invalid parameters need correction, permissions need a state change, and only some transient quote or busy-context failures justify bounded retries.

Can Pineify explain an MQL4 error log?

Pineify can revise a self-contained .mq4 file using the error, failed call, and relevant code. Runtime and broker evidence still comes from your MT4 environment.

Official references

Related MQL4 resources

Error handling in MQL4 MQL4 compile errors MQL4 AI Coding Agent

Last verified against the linked official references on August 10, 2026. Compile and test the final source in the MetaTrader 4 build, broker, symbol, and account environment you plan to use.

Continue with one reviewable MQL4 file

Define the requirement, inspect the generated source, repair diagnostics, and test the behavior in your own MT4 environment.

Open Coding Agent