Qlik Sense QMC and HUB are not opening

There are many reasons that a QMC and hub will not open, this explains one of them while getting the following error.

Error 404 - Not found The following URL is unknown: /qmc

Environment:
     Qlik Sense Enterprise all versions

The virtual proxy/virtual proxy configuration was changed and is unknown to the current administrator.

It is expected that one has determined port 443 is available, antivirus is disabled/folders excluded, and other measures to solve the problem have been exhausted. 

- Use this article " How to backup PostgreSQL database in Qlik Sense " and take a backup of the database (QSR).
- Open the database using PGAdmin4, use this article -> Installing and Configuring PGAdmin 4 to access the PostgreSQL database used by Qlik Sense

!!! NOTE: MAKE NO CHANGES IN THE DATABASE !!!

- Navigate to table "ProxyServiceSettings"
  Right Click on ProxyServiceSettings -> View Data -> View All rows
  The default listen port is 443, if this is different than 443, maybe 1443 then the URL will need the port specified as https://yourServerURL:1443/qmc

Next
- Navigate to the table "VirtualProxyConfigs"
   Right Click on VirtualProxyConfigs -> View Data -> View All rows
   The 'Description' column has a field containing "Central Proxy (Default)"
   The row containing the "Central Proxy (Default)" has a 'Prefix' column next to it which is empty by default.
        > If the Prefix field is populated then this prefix name will need to be in the URL to access the QMC.
               - For Example https://yourServerURL/prefixName/qmc

Again, do not make the changes to any of the mentioned fields in the database.