Unable to login to an ArcGIS Monitor Server application

Description

When attempting to log in to an ArcGIS Monitor Server application, after the home page loads, the page is redirected to the login page. This issue occurs after ArcGIS Monitor, the counters, and administrator tasks are setup and working correctly.

Checking the network trace when attempting to log in displays an error 400 message for 'https://monitor.domain/rest/api/monitor/statusSummary'.

Cause

ArcGIS Monitor is incompatible with newer versions of MongoDB. The newer versions prevent users from logging in to the ArcGIS Monitor Server applications.

For more information on ArcGIS Monitor system requirements, refer to ArcGIS Enterprise: ArcGIS Monitor system requirements.

Solution or Workaround

Navigate to the MongoDB download page, and download MongoDB version 4.0. After downloading MongoDB, uninstall and reinstall both ArcGIS Monitor and MongoDB.

Warning:   
The following workaround removes and reinstalls ArcGIS Monitor, reverting the deployment to its default state.

1. Remove all monitors set up on the ArcGIS Monitor machine. For steps, refer to Steps 1 through 6 in ArcGIS Monitor: Rename monitor services.
2. Uninstall ArcGIS Monitor.
3. Uninstall MongoDB.
4. Navigate to the ArcGIS Monitor directory, and delete all the data in the folder. The default installation directory is:

C:\ArcGIS Monitor

5. Navigate to the MongoDB data directory. If this directory is not within the installation directory, remove all the files.
6. Reinstall MongoDB. For more information, refer to ArcGIS Monitor: Database requirements for the Monitor Server application.
7. Reinstall ArcGIS Monitor. For steps, refer to ArcGIS Enterprise: Install ArcGIS Monitor.