Enterprise Console crashes when adding a distribution description in the Update Manager

Issue
After editing an Update Manager's configuration and then clicking OK, Enterprise Console crashes.

Known to apply to the following Sophos product and version:
Enterprise Console, version 4

What to do

This error occurs when you add a description to the default distribution.

Re-open Enterprise Console and edit the Update Manager, leaving the description field in the default distribution blank.

This is a known issue, which was fixed in Enterprise Console, version 4.5.