SharePoint Pain

Applies to SharePoint 2016; not tested on other versions of SharePoint.   Symptoms   https://caUrl/_admin/TimerJobHistory.aspx?View=5 shows continuous failures of the “Persisted Navigation Term Set Synchronization” job, which begins shortly after 06:00.   Error Messages   There was no endpoint listening at http://<servername 02> :32843/d93d2dec585f4ebfbf47591fc1d8dd3d/MetadataWebService.svc that could accept the message. This is often caused by an incorrect address or SOAP action. See InnerException, if present, for more details.. (Correlation=9e6b2ba1-d1f4-1019-9297-1728042606ca)   There was no endpoint listening at http://<servername 01> :32843/d93d2dec585f4ebfbf47591fc1d8dd3d/MetadataWebService.svc that could accept the message. This is often caused by an incorrect address or SOAP action. See InnerException, if present, for more details.. (Correlation=9e6b2ba1-71af-1019-9297-1d5b64a5c2e0) The “endpoint listening” URL is going back and forth b...

Symptoms   The browser shows “Sorry, something went wrong” intermittently when you access any pages on SharePoint:   The associated Correlation ID shows the following error on the affected frontend server even though all services and resource utilizations are up and running as expected:   System.InvalidOperationException: Operation is not valid due to the current state of the object.   at Microsoft.SharePoint.SPUserToken.GetClaimsUserKey()    at Microsoft.SharePoint.SPGlobal.CreateSPRequestAndSetIdentity(SPSite site, String name, Boolean bNotGlobalAdminCode, String strUrl, Boolean bNotAddToContext, Byte[] UserToken, SPAppPrincipalToken appPrincipalToken, String userName, Boolean bIgnoreTokenTimeout, Boolean bAsAnonymous)    at Microsoft.SharePoint.SPWeb.InitializeSPRequest()    at Microsoft.SharePoint.SPWeb.EnsureSPRequest()    at Microsoft.SharePoint.SPWeb.get_Request()    at Microsoft.S...