During the Windows 10 upgrade the machines get stuck on 75 % for hours. When the machine is switched of at this stage it rolls back to the previous OS and you get the error message as below.
In place upgrade deployed via SCCM 1511.
All Software Updates installed via SCCM Software Update Point.
The 0xC1900101 – 0x4000D error point me to the sites below which advised to run “sfc /scannow” and “System Update Readiness Tool”. Both of them returned no errors or any issues.
Another site https://www.reddit.com/r/Windows10/comments/3fgigq/possible_fix_for_error_0xc1900101_0x4001e_and/ advised to run “Windows update troubleshooter”. I ran the troubleshooter and it fixed a couple of things but there was 2 errors it couldn’t fix. Error Code : 80244022. The client was unable to check for updates. I checked the log files and the wuahandler.log pointed me to http://eskonr.com/2014/02/configmgr-onsearchcomplete-failed-to-end-search-job-error-0x80244022-wuahandler-log/which lead me to check WSUS and IIS on the Software Update Point.
I then noticed that the WSUSpool Application Pool in IIS was stopped.
I started the Application Pool and tried the Update again and it was successful. I also increased the memory allocated to the pool to 4gb.
After this the build went past 75 %. This mean that at this point in the upgrade process the machine try and connect to the source where the machine receive updates from and because the application pool was stopped no machine were able to connect and therefore just got stuck on 75 %.