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ErrorLib — Industrial Fault Code Library

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255

Operation Not Activated (Invalid Mode/Block Executing)

Fanuc · Alpha i series AC Servo Motor

What does 255 mean?

Operation cannot be activated because either an invalid mode is specified or a block execution is currently in progress. The system is either in an incompatible state or busy.

Common Causes

  • Invalid mode specified for the requested operation.
  • A block execution is currently in progress, preventing activation of a new operation.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the current operating mode for compatibility.

  2. 2

    Verify whether a block is currently being executed; wait for it to stop before activating a new operation.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

000Power-Down Required Parameter011Zero Feedrate Specified013Maximum Feedrate Zero
Source: Fanuc Alpha i series AC Servo Motor
Open Manual (Page 223)Search more codes in this manual