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Unable to upload CSV file: The Read Only Field Assigned To Extension Has Changed


After downloading a CSV file from Account Manager, you are unable to upload it back in.

The following error is displayed: "The Read Only field Assigned To extension has changed."

Applies To

  • Account Manager
  • File Uploads


Add missing 0 to Extensions.

  1. Download the CSV file.
  2. Find the extensions fields that are missing the leading 0 > add in 0.
  3. Import the amended file back into Account Manager.


Your account may have extensions configured with leading 0's, e.g. 0556, 0784, etc.

During the Excel export process, the 0 is removed if an entry is identified as beginning with a 0. Therefore, an extension such as 0556 simply appears as 556.