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ErrorLib — Industrial Fault Code Library

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20-1

Required license missing or expired

Allen-Bradley · Logix 5000

What does 20-1 mean?

A required license is either missing or has expired during the controller's transition to run or test mode. This prevents the controller from entering an operational state.

Common Causes

  • Required license missing or expired during transition to run or test mode

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Insert a CmCard containing all licenses required by the project in the controller.

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

Related Faults

00D0No block-transfer response (timeout)00D1Checksum mismatch in read response00D2Read/Write request/response mismatch
Source: Logix 5000
Open Manual (Page 158)Search more codes in this manual