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https://help.tallysolutions.com/docs/te9rel61/Licensing/Error_Code_6266.htm

Error Code 6266: Invalid or incorrect e-mail ID. Enter valid account administrator or site administrator e-mail ID to proceed.

Cause

This error occurs when you provide an e-mail ID which is not authorised to perform any of the license operations.

Solution

You must enter a valid administrator or site administrator e-mail ID to perform any licensing operations.