php data_processing ai_generated true

json_decode(): Maximum stack depth exceeded

ID: php/json-max-depth

Also available as: JSON · Markdown
88%Fix Rate
90%Confidence
45Evidence
2023-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
83 active — — —

Root Cause

JSON max depth errors occur when json_decode() encounters a JSON structure nested deeper than the default 512 levels. This can indicate deeply nested API responses, recursive data structures, or malicious payloads designed to cause resource exhaustion.

generic

Workarounds

  1. 90% success Increase the depth parameter to a reasonable value based on expected data structure 
    Pass a larger depth as the third argument: json_decode($json, true, 1024). Choose a value based on the known maximum nesting of your data. Values between 512 and 2048 are safe for most use cases.
  2. 85% success Validate and limit nesting depth before processing untrusted JSON 
    For untrusted input, use a streaming JSON parser (e.g., JsonMachine) that processes tokens incrementally without building the full structure in memory. Alternatively, validate depth with a simple counter before calling json_decode().

Dead Ends

Common approaches that don't work:

  1. Setting the depth parameter to PHP_INT_MAX 72% fail

    Extremely deep recursion in JSON parsing can exhaust the C-level stack, causing a segfault rather than a PHP error. It also opens the application to denial-of-service attacks via crafted deeply nested JSON payloads.

  2. Pre-processing the JSON string with regex to flatten it before decoding 80% fail

    Regex-based JSON manipulation is inherently fragile and will break on escaped characters, unicode sequences, and edge cases. It also adds significant processing overhead for large payloads.

Error Chain

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