Attempts to install or upgrade ArcGIS Enterprise fail, and return the following error:
Error: User name is longer than 20 characters.
This is a known limitation when using the user principle name (UPN) format which uses the symbol '@', for example, email@example.com as the Portal for ArcGIS Windows service account. This results in ArcGIS Enterprise counting the domain together with the username and returns the error.
Install ArcGIS Enterprise
When specifying the ArcGIS Enterprise Windows service account name, use the domain/username format and ensure the username contains less than 20 characters. ArcGIS Enterprise only counts the username portion of the account name and omits the domain portion when counting the number of characters.
Upgrade ArcGIS Enterprise