MQL4 ERR_FILE_NOT_EXIST
MQL4 error 5020 file does not exist maps to ERR_FILE_NOT_EXIST: file does not exist. The requested file is not present at the relative location visible to the program, tester, or shared-file mode. 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 5020 ERR_FILE_NOT_EXIST and defines it as “file does not exist.” The requested file is not present at the relative location visible to the program, tester, or shared-file mode.
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.
Retry only after the file is created, copied, or addressed through the correct sandbox.
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 file was not deployed under MQL4/Files | Place the file in the data folder used by the running program. |
| Strategy Tester looks under Tester/Files instead of the live terminal folder | Copy test fixtures into Tester/Files for Strategy Tester runs. |
| The relative folder, name, case, or extension does not match | Log and compare the exact relative name including its extension. |
| FILE_COMMON is set on one side but not the other | Use FILE_COMMON consistently when shared storage is part of the design. |
The script shows the relative file name and checks FileOpen against INVALID_HANDLE. The same source can see different folders in live and tester contexts.
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 5020, symbol, prices, volume, ticket, and terminal state relevant to the operation.
Place the file in the data folder used by the running program.
Compile the revised source, then test with the same MT4 build, broker, symbol, account permissions, and market state.
ERR_FILE_NOT_EXIST means file does not exist. The code should still identify which API returned failure and log the inputs used for that call.
The file was not deployed under MQL4/Files Strategy Tester looks under Tester/Files instead of the live terminal folder The relative folder, name, case, or extension does not match FILE_COMMON is set on one side but not the other
Retry only after the file is created, copied, or addressed through the correct sandbox.
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