I am on Windows 10 and I regularly get this pop up when I open Plastic. I removed the hostnames from the message I pasted above for security reasons. The only way I recover from this is to go to C:\Users\<username>\AppData\Local\plastic4\ folder and delete the guivisualstate.xml file. Evidently this has something to do with server certificates etc. There is an outdated help page which asks you to create a self signed certificate using makecert but there is no makecert anymore in Windows 10. See this thread We need to use New-SelfsignedCertificate See thread https://docs.microsoft.com/en-us/windows/win32/seccrypto/makecert Can someone help me? I am going crazy with this issue and I have been living with it for 2 years now.