USAGEFAULT | Usage fault exception

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Systems & Devices

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/systems/embedded-systems/error-codes/usagefault/

Last Updated

Feb 27, 2026

Summary

The CPU detected an illegal instruction, undefined state, or invalid execution condition.

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Guides

Embedded / IoT Device Error Codes: Firmware, Connectivity, and Hardware Fault Patterns

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What This Code Means

Usage faults on Cortex‑M style systems can occur when the CPU executes an undefined instruction, divides by zero (if trapped), or enters an invalid state. It often points to corrupted code flow, stack issues, or jumping to an invalid address.

Where Users Usually See This Code

Crash logs during runtime
After firmware updates or new feature rollouts

Why This Code Appears

Function pointer/callback points to invalid memory
Stack corruption changed the return address
Binary built for the wrong CPU/ABI settings

What Typically Happens Next

Device resets or enters a fault handler loop

What This Code Is Not

It is not a network or cloud service error
It is not necessarily hardware failure

Troubleshooting Checklist

□ Capture PC/LR values and stack trace if available
□ Validate firmware build settings for the target MCU
□ Review recent code changes around interrupts, callbacks, and stack usage

Notes And Edge Cases

UsageFault may be masked into HardFault if fault configuration differs by firmware.

Related Codes

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