MQL4 ERR_WRONG_FILE_NAME
MQL4 FileOpen error 5002 wrong file name maps to ERR_WRONG_FILE_NAME: wrong file name. The file name or relative path passed to the file API is not valid for the MT4 file sandbox. Capture GetLastError immediately after the failed call, correct the cause, and retry only when the condition can change.
Open the Coding Agent, then choose MQL4 from the language menu.
#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);
}The official MQL4 runtime table names error 5002 ERR_WRONG_FILE_NAME 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.
The error number is evidence about one failed call, not a diagnosis of the whole EA. Read the API sentinel first, then call GetLastError immediately because that function returns the current _LastError value and resets it.
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.
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.
| Check | Action |
|---|---|
| The path is empty, malformed, absolute, or contains unsupported characters | Use a non-empty relative name under the documented file sandbox. |
| A user input is concatenated into the path without validation | Allow only expected folder, base-name, and extension characters. |
| Directory separators or extensions differ from the deployed file | Build and log the final relative path in one place. |
| The code confuses an external operating-system path with an MQL4 sandbox path | Use FILE_COMMON only when shared-terminal storage is intended. |
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.
#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);
}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 AgentStatic diagnostics do not prove runtime behavior, backtest results, broker compatibility, or live-trading safety.
Check the API return value before interpreting an error number from the log.
Call GetLastError immediately and record error 5002, symbol, prices, volume, ticket, and terminal state relevant to the operation.
Use a non-empty relative name under the documented file sandbox.
Compile the revised source, then test with the same MT4 build, broker, symbol, account permissions, and market state.
ERR_WRONG_FILE_NAME means wrong file name. The code should still identify which API returned failure and log the inputs used for that call.
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
Correct the file name before calling FileOpen again. Retrying an invalid path is not useful.
It reports the current _LastError value and resets it. Other operations can change the error state, so a delayed read may describe the wrong call.
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.
Last verified against the linked official references on . Compile and test the final source in the MetaTrader 4 build, broker, symbol, and account environment you plan to use.
Define the requirement, inspect the generated source, repair diagnostics, and test the behavior in your own MT4 environment.
Open Coding Agent