Customer was upgrading to ITMS 8.5 and kept getting blue screens at different places during the upgrade. Blue screens were seen:
No message. No clear indication in Event Log. Customer had Memory Dump analyzed by Microsoft.
Issue caused by Microsoft. Code regression introduced in March 12, 2019 updates KB4489883 and KB4489881 which has a known tcp/winsock regression bug.
Customer had installed KB4489881, but not applied April updates yet.
Make sure you are up-to-date with Microsoft Patches. You will need to install the April Security Only KB4493467 or the April Monthly Cumulative rollup KB4493446 and reboot.
MS KBs mentioned are applicable to Server 2012 R2.