I'm using Sitecore 9.3, Suddenly I faced an error that causes the CM server to be down, and I'm not able to access it.
I checked the logs and this is what I found:
ERROR Error while instantiating agent. Definition: <agent type="Sitecore.Tasks.UrlAgent" method="Run" interval="00:15:00" patch:source="ProjectName.Web.config" xmlns:patch="http://www.sitecore.net/xmlconfig/"><LogActivity>true</LogActivity></agent>
This is the OOB Sitecore task, I don't know why this happen, we have many scheduled tasks, but all run as usual and this happened suddenly out of the blue.