MT5 error 5004: File opening error

What MQL5 says

5004 ERR_CANNOT_OPEN_FILE

File opening error

From MQL5's table of runtime errors, read 24 October 2026. An Expert Advisor reads it with GetLastError() after a call fails; the Experts tab prints what the EA logs.

What causes it

FileOpen() couldn't open the file. MQL5's FileOpen page keeps files in a sandbox: MQL5\Files of the terminal (the testing agent's MQL5\Files in the tester), or the folder shared by all terminals with FILE_COMMON. A full path outside it can't be opened.

The fix in MQL5

Pass a name relative to MQL5\Files, add FILE_COMMON for a file several terminals share, and check for INVALID_HANDLE, which FileOpen() returns when it fails.

void SaveLog()
  {
   int f = FileOpen("C:\\Trading\\log.csv", FILE_WRITE | FILE_CSV);   // outside the file sandbox
   FileWrite(f, TimeCurrent(), _Symbol);
   FileClose(f);
  }

void SaveLog()
  {
   // relative to MQL5\Files of this terminal; add FILE_COMMON for the folder all terminals share
   int f = FileOpen("log.csv", FILE_WRITE | FILE_CSV);
   if(f == INVALID_HANDLE)
     {
      Print("FileOpen failed: ", GetLastError());
      return;
     }
   FileWrite(f, TimeCurrent(), _Symbol);
   FileClose(f);
  }

Both compile in MetaEditor 5 with no errors or warnings. Adapt them to your EA; they were not run against a trade server.

The same error in MT4

MT4 reports it as an error code instead: MT4 error 5004: Cannot open file.

Other MT5 errors

• MT5 error 4014: Function is not allowed for call
• MT5 error 4753: Position not found
• MT5 error 4756: Trade request sending failed
• MT5 error 4802: Indicator cannot be created
• MT5 error 4806: Requested data not found
• MT5 error 10004: Requote
• MT5 error 10006: Request rejected
• MT5 retcode 10009: Request completed
• MT5 error 10013: Invalid request
• MT5 error 10014: Invalid volume in the request
• MT5 error 10015: Invalid price in the request
• MT5 error 10016: Invalid stops in the request
• MT5 error 10017: Trade is disabled
• MT5 error 10018: Market is closed
• MT5 error 10019: There is not enough money to complete the request
• MT5 error 10021: There are no quotes to process the request
• MT5 error 10022: Invalid order expiration date in the request
• MT5 error 10026: Autotrading disabled by server
• MT5 error 10027: Autotrading disabled by client terminal
• MT5 error 10030: Invalid order filling type
• MT5 error 10031: No connection with the trade server
• MT5 error 10044: The request is rejected, because the "Only position closing is allowed" rule is set for the symbol
• MT5 error 10046: The request is rejected, because the "Opposite positions on a single symbol are disabled" rule is set for the trading account.