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MQL5 error directory

MQL5 Errors: Find the Right Code and Fix

MQL5 errors come from distinct layers: MetaEditor compilation, terminal runtime, request precheck, and trade server response. Identify where the number was produced before applying a fix. This directory covers 38 focused MQL5 error and symptom guides, each linked to the relevant official MQL5 reference and a reproducible diagnostic pattern.

Open MQL5 Coding AgentReview the diagnostic example

Open the Coding Agent and choose MQL5 from the language menu.

Log each error layer.mq5
ResetLastError();
bool sent=OrderSend(request,result);
int runtime_error=GetLastError();

PrintFormat("sent=%s runtime=%d retcode=%u comment=%s",
            sent ? "true" : "false",
            runtime_error,result.retcode,result.comment);
  • 39 indexed pages
  • 4 diagnostic layers
  • Official references linked
  • MQL5-specific repair examples

Also searched as: common errors in mql5; common errors in mql5 programming; mql5 error.

Browse all MQL5 error guides

Select the layer that produced the message, then open the focused guide for its official meaning and repair path.

Choose the error namespace first

The same numeric value can be meaningless without its source. Copy the full MetaEditor message, the GetLastError call site, or the MqlTradeResult field that produced it.

LayerWhere to read itWhat it controls
CompilationMetaEditor build outputWhether EX5 can be created
Terminal runtimeGetLastErrorClient API operation
Trade precheckMqlTradeCheckResult.retcodeRequest and projected account state
Trade serverMqlTradeResult.retcodeServer processing outcome

A reliable MQL5 diagnostic record

Save enough context to reproduce the failure without exposing account credentials. For code errors, keep file, line, column, function, and build. For runtime and trade failures, keep symbol, timeframe, request fields, return values, retcodes, comments, and server time.

  • Reset the runtime error state before the suspected call.
  • Record the direct function return before reading outputs.
  • Read the trade retcode even when OrderSend returns true.
  • Retest the repair in the intended terminal, broker, symbol, and account mode.

Fix code without hiding behavior problems

A compiler repair can make an EA runnable without making its signals correct. A cleared trade retcode can make an order valid without making the strategy safe. Keep source validation, Strategy Tester behavior, broker constraints, and live risk as separate gates.

Use a focused diagnostic

This diagnostic keeps the function return, terminal runtime code, and trade server retcode separate. Compiler diagnostics remain in MetaEditor and should be resolved before this code can run.

A clean compile or a cleared error code does not prove strategy logic, broker compatibility, backtest quality, or live-trading safety. Reproduce the result in the target MetaTrader 5 terminal and account environment.

Log each error layer.mq5
ResetLastError();
bool sent=OrderSend(request,result);
int runtime_error=GetLastError();

PrintFormat("sent=%s runtime=%d retcode=%u comment=%s",
            sent ? "true" : "false",
            runtime_error,result.retcode,result.comment);
Where Pineify fits

Repair editable MQL5 source with compiler feedback

Pineify can generate or revise MQL5 source and use MQL5 compilation diagnostics during the coding workflow. Keep the exact error, source location, program type, and intended behavior in the request so the change remains reviewable.

Open MQL5 Coding Agent

Pineify does not run your broker terminal, Strategy Tester, market data, or live orders. Validate the final program in your own MetaTrader 5 environment.

Review MQL5 AI Coding Agent capabilities
Pineify MQL5 AI Coding Agent with an editable MetaTrader 5 code artifact

A practical verification workflow

  1. 1

    Capture the full message

    Record the code, description, call or compiler location, and the program state that produced it.

  2. 2

    Classify the layer

    Decide whether the source is MetaEditor, GetLastError, OrderCheck, or MqlTradeResult.retcode.

  3. 3

    Open the focused guide

    Use the directory below to check the official meaning, required inputs, and smallest repair.

  4. 4

    Reproduce after repair

    Compile, run a controlled test, and keep the new diagnostic record with the result.

Frequently asked questions

Where can I find MQL5 error meanings?

Use the official compilation, runtime, and trade server code tables according to the source of the number. This directory links those references and focused repair pages.

Is GetLastError enough for OrderSend failures?

No. Keep the OrderSend boolean, GetLastError, and MqlTradeResult.retcode plus comment. They describe different stages of the operation.

Can Pineify fix every MQL5 error automatically?

Pineify can generate and revise MQL5 source and use compilation diagnostics in its coding workflow. Broker state, terminal permissions, historical data, Strategy Tester configuration, and live behavior still require checks in your MT5 environment.

Last verified against the linked official references on . Compile and test the final source in the MetaTrader 5 build, broker, symbol, and account environment you plan to use.

Continue with reviewable MQL5 source

Provide the exact diagnostic and intended behavior, inspect the generated change, compile it, and verify it in your MT5 test environment.

Open MQL5 Coding Agent