MQL4 ERR_ZERO_DIVIDE

MQL4 zero divide 4013: guard every denominator

MQL4 zero divide 4013 maps to ERR_ZERO_DIVIDE: zero divide. A calculation attempted to divide by zero, often after an empty sample or unchanged price range. This is a critical runtime error that terminates the program immediately; prevent it before the division rather than expecting a later GetLastError call to recover. 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 Agent Review the code example

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

SafeDivision.mq4MQL4

#property strict
#property script_show_inputs

input double Numerator = 10.0;
input double Denominator = 0.0;

void OnStart()
  {
   if(Denominator == 0.0)
     {
      Print("Calculation stopped: denominator is zero.");
      return;
     }

   double result = Numerator / Denominator;
   if(!MathIsValidNumber(result))
     {
      Print("Calculation produced an invalid number.");
      return;
     }

   Print("Result: ", DoubleToString(result, 6));
  }

Official meaning: zero divide
Check API results or the runtime failure log
Capture relevant inputs and error context
Retry only when the condition can change

What MQL4 error 4013 means

The official MQL4 runtime table names error 4013 ERR_ZERO_DIVIDE and defines it as “zero divide.” A calculation attempted to divide by zero, often after an empty sample or unchanged price range. This is a critical runtime error that terminates the program immediately; prevent it before the division rather than expecting a later GetLastError call to recover.

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.

A denominator input is zero or was never initialized
A range such as high minus low equals zero
A count remains zero because no bars or orders matched
An invalid numeric result flows into a later calculation

Fix the cause, then choose a retry policy

Do not retry the same calculation. Correct the data or branch for the zero case, then rerun the calculation with a defined result.

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
A denominator input is zero or was never initialized	Check the denominator before every division and define the zero case explicitly.
A range such as high minus low equals zero	Skip or substitute only when the strategy specification defines that behavior.
A count remains zero because no bars or orders matched	Check the matched count before calculating an average.
An invalid numeric result flows into a later calculation	Use MathIsValidNumber after calculations that can produce invalid values.

Review the complete example

The script rejects a zero denominator before division and checks that the result is a valid number. The correct fallback depends on the indicator or strategy rule.

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

SafeDivision.mq4MQL4

#property strict
#property script_show_inputs

input double Numerator = 10.0;
input double Denominator = 0.0;

void OnStart()
  {
   if(Denominator == 0.0)
     {
      Print("Calculation stopped: denominator is zero.");
      return;
     }

   double result = Numerator / Denominator;
   if(!MathIsValidNumber(result))
     {
      Print("Calculation produced an invalid number.");
      return;
     }

   Print("Result: ", DoubleToString(result, 6));
  }

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.

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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
Locate the failed operation
Check the API result, or the terminal log and source location for a critical runtime failure.
2
Capture the error once
For a recoverable API failure, capture GetLastError immediately. For a terminated program, preserve the terminal log. Record error 4013 and the inputs relevant to the failed operation.
3
Correct the triggering condition
Check the denominator before every division and define the zero case explicitly.
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 zero divide 4013 mean?

ERR_ZERO_DIVIDE means zero divide. Use the API result or critical runtime log, together with the relevant inputs, to identify the failed operation.

What usually causes MQL4 error 4013?

A denominator input is zero or was never initialized. A range such as high minus low equals zero. A count remains zero because no bars or orders matched. An invalid numeric result flows into a later calculation.

Should an EA retry after error 4013?

Do not retry the same calculation. Correct the data or branch for the zero case, then rerun the calculation with a defined result.

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 4013?

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.

Official references

Related MQL4 resources

MQL4 error code reference Error handling in MQL4 MQL4 AI Coding Agent

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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