HTTP 500 Internal Server Error every 40-50 days

We have had a problem with DocuWare since late 2018.  Every 40 to 50 days, our users will open the web client and get a HTTP 500 Internal Server Error.  The only fix is a server reboot.  I went through all the logs, and found these common errors on the dates we had the issues.

• AcceptSecurityContext failed. Error Code = 2148074248 > The token supplied to the function is invalid
• AcquireCredentialsHandle failed, Error: 2148074245 > The requested security package does not exist
• Cannot find active authentication server. All servers are either stopped or the communication channel settings don't allow a connection.
• Can not connect to the remote host "gtcp://<servername>:9000". System error message: No connection could be made because the target machine actively refused it 10.0.0.114:9000.
• Login token expired
• No suitable active server AuthenticationServer with guid 3a3486ec-725c-4806-95db-5d256d5da0b4 found. Server connections excluded (already tried to connect): 26263075-9716-400e-a654-9aea7fd9ff3b. Reason: Requested Service not found
• System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
• System.NullReferenceException: Object reference not set to an instance of an object.
• The response has not been received within the specified period of time.

I looked at the dates when we had issues.

1. The first round of issues were on 9/10/18 followed by 10/10/18 and 10/22/18 – at that point DW installed HotFixPack24 and HotFix36 on 11/16/18. That seemed to fix our issues until 3/25/19.
2. The 2^nd round started on 3/25/19 followed by 5/3/19 – at that point DW installed HotFixPack40 on 5/11/19. That seemed to fix our issues until 9/20/19
3. The 3^rd and most recent round of issues started on 9/20/19, then 11/4/19, then 12/26/19, then 2/7/20. Each time the failure was between 43 and 52 days so the next failure should be between 3/21/20 and 3/30/20.

It seems like whenever we install hotfixes, it fixes the issue for 140-154 days but then it comes back. And if we don’t apply another hotfix, the issue reoccurs every 39-52 days. Does that make any sense?

Support says they need to see the server in a failed state, so i will have to wait another 10-20 days to get to that point. But i'm hoping im not the first to see this or maybe someone else has seen it.

Thanks
 

Prior to a reboot have you tried restarting IIS to see if that salves the issue?

solves*