Dynamics 365 onpremise unable to browse and down situation. On the findings from Event viewer events captured with below.
The validity of CRMTokenKey managed by Dynamics CRM Async service (Maintenance), and this Tokenkeys are automatically generated for every 24 hours, somehow or generic issue that sometime this key was unable to generate automatically and its makes the application down.
To Resolve this issue Restart of Dynamics CRM Services and IISRESET should fix the issue Or you can you can run the below command.
1) Open Command Prompt with Run as Administrator.
2) To Enter in to the location use CD C:\Program Files\Microsoft Dynamics CRM\Tools
3) Run Microsoft.Crm.Tools.WRPCKeyRenewal /R
4) Do IISRESET
Gook Luck !