MQL4 ERR_WEBREQUEST_REQUEST_FAILED
MQL4 error 5203 HTTP request failed maps to ERR_WEBREQUEST_REQUEST_FAILED: hTTP request failed. WebRequest could not complete the request; URL permission, connection, TLS, timeout, or endpoint state may be involved. 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
#property script_show_inputs
input string Url = "https://example.com/health";
void OnStart()
{
if(StringFind(Url, "http://") != 0 && StringFind(Url, "https://") != 0)
{
Print("Invalid URL: ", Url);
return;
}
char request_data[];
char response_data[];
string response_headers;
ResetLastError();
int status = WebRequest("GET", Url, "", 5000, request_data,
response_data, response_headers);
if(status == -1)
Print("WebRequest failed. error=", GetLastError(),
". Check the allowed URL list and connection.");
else
Print("HTTP status: ", status);
}The official MQL4 runtime table names error 5203 ERR_WEBREQUEST_REQUEST_FAILED and defines it as “HTTP request failed.” WebRequest could not complete the request; URL permission, connection, TLS, timeout, or endpoint state may be involved.
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.
Use a bounded delayed retry only for a transient network or server failure. Do not retry invalid permissions, tester restrictions, or malformed requests.
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 host is missing from the terminal list of allowed URLs | Add the exact scheme and host to the allowed URL list when the endpoint is trusted. |
| The terminal has no connection or the request times out | Use a bounded timeout and log connection state and elapsed time. |
| TLS, DNS, proxy, firewall, or endpoint availability blocks the request | Test the endpoint and certificate path outside the EA without exposing secrets. |
| The call is attempted in Strategy Tester, where WebRequest is unavailable | Provide deterministic test data instead of calling WebRequest in Strategy Tester. |
The script checks the URL, sets a finite timeout, and captures GetLastError when WebRequest returns -1. It does not log credentials or request bodies.
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
#property script_show_inputs
input string Url = "https://example.com/health";
void OnStart()
{
if(StringFind(Url, "http://") != 0 && StringFind(Url, "https://") != 0)
{
Print("Invalid URL: ", Url);
return;
}
char request_data[];
char response_data[];
string response_headers;
ResetLastError();
int status = WebRequest("GET", Url, "", 5000, request_data,
response_data, response_headers);
if(status == -1)
Print("WebRequest failed. error=", GetLastError(),
". Check the allowed URL list and connection.");
else
Print("HTTP status: ", status);
}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 5203, symbol, prices, volume, ticket, and terminal state relevant to the operation.
Add the exact scheme and host to the allowed URL list when the endpoint is trusted.
Compile the revised source, then test with the same MT4 build, broker, symbol, account permissions, and market state.
ERR_WEBREQUEST_REQUEST_FAILED means hTTP request failed. The code should still identify which API returned failure and log the inputs used for that call.
The host is missing from the terminal list of allowed URLs The terminal has no connection or the request times out TLS, DNS, proxy, firewall, or endpoint availability blocks the request The call is attempted in Strategy Tester, where WebRequest is unavailable
Use a bounded delayed retry only for a transient network or server failure. Do not retry invalid permissions, tester restrictions, or malformed requests.
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