SCCM upgrade woes

[JLogan3o13]

Admittedly this is more to vent than anything, but if any SCCM folks (*cough* @Jon *cough*) have seen similar, I would love to hear about it.

I am working with a university customer, upgrading SCCM from R2 RTM to 1511. They have two domains, with separate instances of SCCM. On the one side, the upgrade went just fine a while back. On the other side, I performed the upgrade this past weekend and it was a complete PITA. The upgrade itself went off without a hitch: I created a clone of the SCCM VM, upgraded following the link below, and everything looked successful. I was able to image a machine just fine.

The issue came in when testing application deployment. I noticed when logging into a couple of test target machines that the client refused to update. I was receiving the following errors in the ccm.log file:

---> WNetAddConnection2 failed (LOGON32_LOGON_NEW_CREDENTIALS) using account <service account name> (00000035)  SMS_CLIENT_CONFIG_MANAGER   6/11/2016 8:42:09 PM    8424 (0x20E8)---> 

ERROR: Unable to access target machine for request: "2097157029", machine name: "HT8250",  access denied or invalid network path.   SMS_CLIENT_CONFIG_MANAGER   6/11/2016 8:42:22 PM    5032 (0x13A8)

Execute query exec [sp_CP_SetLastErrorCode] 2097157029, 53  SMS_CLIENT_CONFIG_MANAGER   6/11/2016 8:42:22 PM    5032 (0x13A8)

This is odd to me, as that particular error is often due to a DNS or firewall issue. Regarding DNS, I was able to ping and perform nslookup both ways, from site server to client and vice versa. I also disabled firewall altogether for testing, but this did not resolve the issue. The error also states it is receiving an access denied when attempting to hit the Admin share on the client machine. However, if I log into another machine with the Client Installation service account credentials, I can hit the Admin Share just fine. I also removed and re-added the service account under Site Configuration>>Sites>>Client Push Installation Properties, which gives me the option to test the configuration. Of course, the test says everything is good 

In the end, I reverted both the SCCM server and the target machines to their pre-upgrade state, and everything picked up right away. But at some point I am going to have to do this again. If anyone has personal experience with similar issues, I would be open to any suggestions.

https://www.systemcenterdudes.com/sccm-1511-upgrade/