ESP32 “Guru Meditation Error: LoadProhibited”: what it means

LoadProhibited means your code read from a memory address that does not exist, nearly always through a pointer that was never set. It is a software bug, not a hardware fault. The backtrace in the serial output tells you which line.

What the message means

The line reads “Guru Meditation Error: Core 1 panic’ed (LoadProhibited). Exception was unhandled.” The core tried to load from an invalid address and stopped. EXCVADDR near 0x00000000 usually means a null pointer.

Fix it in this order

1. Copy the whole crash dump from the serial monitor. The “Backtrace:” line is the useful part.
2. Decode it with the ESP exception decoder for your IDE, or addr2line, to get file and line numbers.
3. Look for pointers, objects or arrays used before they were created: a WiFiClient, sensor object or buffer used before begin().
4. Check array indexes and string lengths where the crash line points.
5. Check that a function returning a pointer did not return null. Check for failed memory allocation.
6. If it crashes only after Wi-Fi events, check callbacks that touch objects freed or not yet created.

Why it happens

LoadProhibited means the code tried to read from an invalid memory address, most often a null or uninitialised pointer. A common cause is using an object before its begin() or constructor has run, or a library function that was handed a missing object.

Read the backtrace in the Serial Monitor, decode it with the exception decoder or addr2line to find the line, and check every pointer and every device object on that path. Check that sensors, files and network clients really started before use.

If you see this, do this

Related

ESP32 pinout for robotics, MQTT telemetry on the ESP32.

Last reviewed: November 2026. These are the usual causes and the order that finds them fastest. Test on your own board; clones and cables differ.