E9.2 C1041 compile error on Full Build requiring /FS switch



Legendary Poster
We are getting the following error on multiple NERs during a full build. Seems to be somewhat random which NERs.

Example Build Compile Error
n76b7010.c(27): fatal error C1041: cannot open program database 'E:\E920\packages\TS920FA\source\CLOC\vc140.pdb'; if multiple CL.EXE write to the same .PDB file, please use /FS

Adding the /FS switch to the CL.exe flags fixes the issue.
Full list of flags in the jde.ini on ES server that gives us a clean build:
OptimizationFlags=/FD /Gz /Oi /Ob1 /Gs /GF /Zi /MD /W4 /EHsc /Gy /Oy- /FS

The flag makes sense to me but have not needed this flag before and just suddenly started getting the error, has anyone seen this or can explain why we suddenly started getting this?

More details:

We have four environments: DV920, TS920, PY920, PD920. TS920 is like another PY and resides on the same ES servers as PY920. We have two ES servers for both DV and TS/PY. We have been testing the build in mainly DV920 and TS920 but I believe we also got the error in PY920 (again, TS/PY share the ES servers). We do NOT get the error in DV920 even w/o the /FS switch. As far as we can tell DV920 and TS920 ES servers are configured identical. However, we did start having complete build failures on TS920 (not the C1041 error) and we found jdesnet.exe was getting quarantined by AV. Once we figured out AV was the culprit we put AV into monitor only mode so it wouldn't quarantine any files on the ES server. However, before we discovered AV was the problem we restored the TS920 ES VMs from a previous backup that was known good (about a week old). So after we restored the TS920 ES server VMs from a backup, then disabled AV the build would finish but then we started getting the C1041 errors.