Pineify logo

MQL4 ERR_FILE_WRONG_FILENAME

MQL4 FileOpen error 5002: correct the file name

MQL4 FileOpen error 5002 wrong file name maps to ERR_FILE_WRONG_FILENAME: wrong file name. The file name or relative path passed to the file API is not valid for the MT4 file sandbox. For API calls, check the return value and capture GetLastError after a documented failure. Critical runtime errors require preventive guards and inspection of the terminal log.

Open MQL4 Coding AgentReview the code example

Open the Coding Agent, then choose MQL4 from the language menu.

FileNameDiagnostic.mq4MQL4
#property strict

void OnStart()
  {
   string file_name = "pineify/diagnostic.csv";
   ResetLastError();
   int handle = FileOpen(file_name, FILE_READ|FILE_CSV|FILE_ANSI);
   if(handle == INVALID_HANDLE)
     {
      Print("FileOpen failed. error=", GetLastError(),
            " file=", file_name);
      return;
     }

   Print("File opened inside the MQL4 file sandbox.");
   FileClose(handle);
  }
  • Official meaning: wrong file name
  • Check API results or the runtime failure log
  • Capture relevant inputs and error context
  • Retry only when the condition can change

What MQL4 error 5002 means

The official MQL4 runtime table names error 5002 ERR_FILE_WRONG_FILENAME and defines it as “wrong file name.” The file name or relative path passed to the file API is not valid for the MT4 file sandbox.

An error-state value is supporting context, not proof that a call failed or a diagnosis of the whole EA. For noncritical API failures, read the return value and then GetLastError, which resets _LastError. Critical errors such as zero division terminate execution, so code after the failing expression cannot serve as a recovery handler.

Check these conditions before editing the strategy

Start with the inputs and external state that existed at the failure point. A later log entry or a successful call can overwrite the useful context.

  • The path is empty, malformed, absolute, or contains unsupported characters
  • A user input is concatenated into the path without validation
  • Directory separators or extensions differ from the deployed file
  • The code confuses an external operating-system path with an MQL4 sandbox path

Fix the cause, then choose a retry policy

Correct the file name before calling FileOpen again. Retrying an invalid path is not useful.

Keep the original trading and risk rules intact. A workaround that widens stops, increases volume, changes an account setting, or ignores a failed return value can hide the symptom while changing the system.

CheckAction
The path is empty, malformed, absolute, or contains unsupported charactersUse a non-empty relative name under the documented file sandbox.
A user input is concatenated into the path without validationAllow only expected folder, base-name, and extension characters.
Directory separators or extensions differ from the deployed fileBuild and log the final relative path in one place.
The code confuses an external operating-system path with an MQL4 sandbox pathUse FILE_COMMON only when shared-terminal storage is intended.

Review the complete example

The script uses a stable relative name, checks INVALID_HANDLE, and logs the name and error at the failure point.

The example improves validation and logging. It does not prove the operation will be accepted by a broker or behave safely in live trading.

FileNameDiagnostic.mq4MQL4
#property strict

void OnStart()
  {
   string file_name = "pineify/diagnostic.csv";
   ResetLastError();
   int handle = FileOpen(file_name, FILE_READ|FILE_CSV|FILE_ANSI);
   if(handle == INVALID_HANDLE)
     {
      Print("FileOpen failed. error=", GetLastError(),
            " file=", file_name);
      return;
     }

   Print("File opened inside the MQL4 file sandbox.");
   FileClose(handle);
  }
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. 1

    Locate the failed operation

    Check the API result, or the terminal log and source location for a critical runtime failure.

  2. 2

    Capture the error once

    For a recoverable API failure, capture GetLastError immediately. For a terminated program, preserve the terminal log. Record error 5002 and the inputs relevant to the failed operation.

  3. 3

    Correct the triggering condition

    Use a non-empty relative name under the documented file sandbox.

  4. 4

    Retest in the target environment

    Compile the revised source, then test with the same MT4 build, broker, symbol, account permissions, and market state.

Frequently asked questions

What does MQL4 FileOpen error 5002 wrong file name mean?

ERR_FILE_WRONG_FILENAME means wrong file name. Use the API result or critical runtime log, together with the relevant inputs, to identify the failed operation.

What usually causes MQL4 error 5002?

The path is empty, malformed, absolute, or contains unsupported characters. A user input is concatenated into the path without validation. Directory separators or extensions differ from the deployed file. The code confuses an external operating-system path with an MQL4 sandbox path.

Should an EA retry after error 5002?

Correct the file name before calling FileOpen again. Retrying an invalid path is not useful.

Why should GetLastError be called immediately?

For a noncritical API failure it reports the current _LastError value and resets it. A delayed read may describe another call. It cannot recover execution after a critical error has terminated the program.

Can Pineify fix MQL4 error 5002?

Pineify can revise a self-contained .mq4 file, add validation and error logging, and return static MetaEditor diagnostics. It cannot prove broker acceptance, account permissions, market availability, or live execution.

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