Maximum function nesting PHP Origin: Application & API Last updated 12 Oct 2026

Fatal error: Maximum function nesting level of '256' reached, aborting!

Recursion went deeper than Xdebug’s max_nesting_level allows (or PHP crashed with a segfault without Xdebug).

Exact message you may see Maximum function nesting level
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Seen on: PHP

Meaning

The message comes from Xdebug. Without Xdebug, infinite recursion in PHP usually ends in a segmentation fault or memory exhaustion.

Common causes

  • Infinite recursion (missing base case)
  • Magic methods calling themselves (__get inside __get)
  • Legitimately deep recursion on big trees

⚡ Quick fix

  1. Find the repeating frames in the trace
  2. Fix the base case
  3. Raise xdebug.max_nesting_level only for legitimately deep recursion

Detailed fix by platform

PHP

  1. Convert deep recursion to an iterative loop with an explicit stack

How to diagnose

  1. Frames — Which function repeats?
  2. Base case — Is it ever reached?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Application & API. Errors that are often confused with or caused by this one (click to open):

Allowed memory size exhausted — PHP Fatal error: Allowed memory size of X bytes exhausted (PHP)Allowed memory size e…ArgumentCountError — Fatal error: Uncaught ArgumentCountError: Too few arguments to function foo(), 1 passed and exactly 2 expected (PHP)ArgumentCountErrorCall to member function on null — Fatal error: Uncaught Error: Call to a member function x() on null (PHP)Call to member functi…Call to undefined function — PHP Fatal error: Uncaught Error: Call to undefined function (PHP)Call to undefined fun…Call to undefined function (WordPress) — WordPress: Fatal error: Uncaught Error: Call to undefined function wp_get_current_user() / add_action() / get_header() (WordPress)Call to undefined fun…Cannot redeclare — Fatal error: Cannot redeclare function foo() (previously declared in …) (PHP)Cannot redeclarePlugin could not be activated because it triggered a fatal error — WordPress: Plugin could not be activated because it triggered a fatal error (WordPress)Plugin could not be a…RangeError — RangeError: Maximum call stack size exceeded (JavaScript)RangeErrorMaximum f…

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