Error in initializing Git Extension

Problem

When initialize git extensions, an exception thrown by the type initializer for GitCommands.AppSettings

Popup window says:

System.Xml.XmlException

Exception Details:

System.TypeInitializationException: An exception was thrown by the type initializer for GitCommands.AppSettings —> System.Xml.XmlException: Unexpected XML declaration. The XML declaration must be the first node in the document, and no white space characters are allowed to appear before it. Line 104, position 9.

Solution

The problem was in the file
/home/user/.local/share/GitExtensions/GitExtensions.exe_Url_fc9221118986807f24034ab13ad4e7143ae90814/user.config

Contain malformed XML.

Remove the file, and problem gone.

Why? No reason found on web. Waiting to see further details.

Source: https://github.com/gitextensions/gitextensions/issues/2710