MT4 error 4051: Invalid function parameter value
Check that call's arguments.
Updated 24 October 2026. Runs in your browser; nothing you type is uploaded.
The number after "error" in MT4's Experts or Journal tab. 161 codes, as MQL4's reference words them.
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What MQL4 says
4051ERR_INVALID_FUNCTION_PARAMVALUE- Invalid function parameter value
From MQL4's table of error codes, read 24 October 2026. An Expert Advisor reads it with GetLastError() after a call fails; the Experts and Journal tabs print what the EA logs.
What causes it
A function got a parameter value outside what it accepts. MQL4's table names no function: it is whichever call set the error before your GetLastError().
How to fix it
Print the arguments of that call just before it and compare each with the parameter list on its page in the MQL4 Reference.
Source: MQL4 Reference: error codes. No MQL4 code is shown because none here was compiled; adapt the steps to your EA.
Other MT4 errors
- MT4 error 0: No error returned
- MT4 error 1: No error returned, but the result is unknown
- MT4 error 2: Common error
- MT4 error 3: Invalid trade parameters
- MT4 error 130: Invalid stops
- MT4 error 131: Invalid trade volume
- MT4 error 132: Market is closed
- MT4 error 133: Trade is disabled
- MT4 error 134: Not enough money
- MT4 error 136: Off quotes
- MT4 error 4107: Invalid price
- MT4 error 4111: Shorts are not allowed
- MT4 error 4112: Automated trading by Expert Advisors/Scripts disabled by trade server
- MT4 error 4200: Object already exists
- MT4 error 5004: Cannot open file
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