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MQL4 ERR_NO_MEMORY_FOR_HISTORY

MQL4 error 4074: reduce history data pressure

MQL4 error 4074 no memory for history data maps to ERR_NO_MEMORY_FOR_HISTORY: not enough memory for history data. The terminal could not allocate enough memory for the requested historical series data. For API calls, check the return value and capture GetLastError after a documented failure. Critical runtime errors require preventive guards and inspection of the terminal log.

Open MQL4 Coding AgentReview the code example

Open the Coding Agent, then choose MQL4 from the language menu.

BoundedHistoryRequest.mq4MQL4
#property strict
#property script_show_inputs

input int Period = 14;

void OnStart()
  {
   if(Period < 1 || Bars <= Period)
     {
      Print("Invalid period or insufficient history: ", Period);
      return;
     }

   ResetLastError();
   double value = iMA(NULL, 0, Period, 0, MODE_SMA, PRICE_CLOSE, 1);
   int error_code = GetLastError();
   if(error_code != 0)
     {
      Print("iMA failed. error=", error_code);
      return;
     }

   Print("SMA: ", DoubleToString(value, Digits));
  }
  • Official meaning: not enough memory for history data
  • Check API results or the runtime failure log
  • Capture relevant inputs and error context
  • Retry only when the condition can change

What MQL4 error 4074 means

The official MQL4 runtime table names error 4074 ERR_NO_MEMORY_FOR_HISTORY and defines it as “not enough memory for history data.” The terminal could not allocate enough memory for the requested historical series data.

An error-state value is supporting context, not proof that a call failed or a diagnosis of the whole EA. For noncritical API failures, read the return value and then GetLastError, which resets _LastError. Critical errors such as zero division terminate execution, so code after the failing expression cannot serve as a recovery handler.

Check these conditions before editing the strategy

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.

  • The program requests many symbols, timeframes, bars, or indicator instances
  • Large arrays duplicate history that MT4 already stores
  • A loop repeatedly loads history without releasing or reusing data
  • The terminal runs under constrained memory with many charts open

Fix the cause, then choose a retry policy

Reduce memory demand before retrying. Repeating the same large history request can make the terminal less stable.

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.

CheckAction
The program requests many symbols, timeframes, bars, or indicator instancesRequest only the symbols, timeframes, and bar range used by the calculation.
Large arrays duplicate history that MT4 already storesReuse buffers and avoid copying full history when a bounded window is enough.
A loop repeatedly loads history without releasing or reusing dataCache successful results and stop repeated history-loading loops.
The terminal runs under constrained memory with many charts openReproduce with fewer charts or indicators and record the terminal build and memory state.

Review the complete example

The script checks a positive period against available bars and reads one iMA value. It imposes no independent memory budget and does not control how much history the terminal loads. Measure memory pressure and limit symbols, periods, and copied ranges separately.

The example improves validation and logging. It does not prove the operation will be accepted by a broker or behave safely in live trading.

BoundedHistoryRequest.mq4MQL4
#property strict
#property script_show_inputs

input int Period = 14;

void OnStart()
  {
   if(Period < 1 || Bars <= Period)
     {
      Print("Invalid period or insufficient history: ", Period);
      return;
     }

   ResetLastError();
   double value = iMA(NULL, 0, Period, 0, MODE_SMA, PRICE_CLOSE, 1);
   int error_code = GetLastError();
   if(error_code != 0)
     {
      Print("iMA failed. error=", error_code);
      return;
     }

   Print("SMA: ", DoubleToString(value, Digits));
  }
Where Pineify fits

Move from the rule to editable MQL4 source

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 Agent

Static diagnostics do not prove runtime behavior, backtest results, broker compatibility, or live-trading safety.

Pineify MQL4 Coding Agent with MQL4 selected and an editable MetaTrader 4 code artifact

A practical workflow

  1. 1

    Locate the failed operation

    Check the API result, or the terminal log and source location for a critical runtime failure.

  2. 2

    Capture the error once

    For a recoverable API failure, capture GetLastError immediately. For a terminated program, preserve the terminal log. Record error 4074 and the inputs relevant to the failed operation.

  3. 3

    Correct the triggering condition

    Request only the symbols, timeframes, and bar range used by the calculation.

  4. 4

    Retest in the target environment

    Compile the revised source, then test with the same MT4 build, broker, symbol, account permissions, and market state.

Frequently asked questions

What does MQL4 error 4074 no memory for history data mean?

ERR_NO_MEMORY_FOR_HISTORY means not enough memory for history data. Use the API result or critical runtime log, together with the relevant inputs, to identify the failed operation.

What usually causes MQL4 error 4074?

The program requests many symbols, timeframes, bars, or indicator instances. Large arrays duplicate history that MT4 already stores. A loop repeatedly loads history without releasing or reusing data. The terminal runs under constrained memory with many charts open.

Should an EA retry after error 4074?

Reduce memory demand before retrying. Repeating the same large history request can make the terminal less stable.

Why should GetLastError be called immediately?

For a noncritical API failure it reports the current _LastError value and resets it. A delayed read may describe another call. It cannot recover execution after a critical error has terminated the program.

Can Pineify fix MQL4 error 4074?

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.

Compile and test the final source in the MetaTrader 4 build, broker, symbol, and account environment you plan to use.

Continue with one reviewable MQL4 file

Define the requirement, inspect the generated source, repair diagnostics, and test the behavior in your own MT4 environment.

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