The following error messages have been found in ALL web apps: "An Existing connection was forcibly closed by the remote host" or "PII is hidden - IDX20804":

Resolution

Add the following configuration to ALL web apps' configuration files (web.config).

<add key="AppContext.SetSwitch:Switch.System.Net.DontEnableSchUseStrongCrypto" value="false" />
<add key="AppContext.SetSwitch:Switch.System.Net.DontEnableSystemDefaultTlsVersions" value="false" />