ASP.NET Settings and Hosting Settings pages of a domain are not opening in Plesk: Argument #1 ($array) must be of type array, null given

Symptoms

• When opening ASP.Net Settings or Hosting Settings of a domain, the page fails to load with one of the following error messages:

  GraphQL Error
  external server error

  Type GraphQL Error
  Message array_values(): Argument #1 ($array) must be of type array, null given

• The following messages are logged in
%plesk_dir%adminlogsphp_error:

  PHP Warning: Undefined array key "version" in C:Program Files (x86)PleskadminplibAspDotNetSettings.php on line 119
  PHP Warning: Trying to access array offset on value of type null; File: C:Program Files (x86)PleskadminplibAspDotNetSettings.php, Line: 119

Cause

Domain's
web.config file contains invalid configuration.

Resolution

Review the content of web.config. Use an online validator to check the syntax of the file. For example:

• https://elmah.io/tools/config-validator/