Plesk ASP site shows 500 error: Operation is not allowed when the object is closed

Symptoms

• ASP site hosted in Plesk shows:

  CONFIG_TEXT: 500 Internal server error.

• The following error can be found in Plesk > Domains > example.com > Logs:

  CONFIG_TEXT: GET / |198|800a0e78|Operation_is_not_allowed_when_the_object_is_closed. HTTP/1.1

• The following error can be found in Failed Request Tracing for a site:

  CONFIG_TEXT: 413. -ASP_LOG_ERROR
  LineNumber    198
  ErrorCode    800a0e78
  Description    Operation is not allowed when the object is closed.
  
  416. -MODULE_SET_RESPONSE_ERROR_STATUS
  ModuleName    IsapiModule
  Notification    EXECUTE_REQUEST_HANDLER
  HttpStatus    500
  HttpReason    Internal Server Error
  HttpSubStatus    0
  ErrorCode    The operation completed successfully.

Cause

Incorrect connection settings to the database server. If the opening of the connection fails server continues processing code as the connection was opened. Thus operations on a closed object are performed. Action statement (INSERT, UPDATE, DELETE) does not return any records, hence the server can't close a non-open recordset.

Resolution

1. Change the website code to include correct connection setting.
2. Install the necessary ASP.NET version according to the Microsoft documentation.
3. Make sure that all requirements necessary for the website are met.