Hi Jason, thanks for replying. I'll check this out from an AV perspective though I have my doubts that is the cause only because the same clients have been able to download/install 3rd party patches from Patch My PC. Those patches are integrated into the MEM, distributed to DPs and clients download them from there, just like any MS update. Having said that, I've seen stupider things happen so the first thing is to rule AV out.

Thanks again.

Hi SharonZhao,

I can't say for sure if the installer threw the same error when the 365 prod suite was installed as I haven't pulled those logs from the PC, but the "teams machine wide installer" did not appear in programs and features after running it and the C:\Program Files (x86)\Teams Installer folder is not present on the system. As a side note the configuration.xml file for 365 is set to install all 365 apps except for Skype and Groove.

We have run the Teams x64 msi as a deployment from SCCM ( so it runs as local SYSTEM) and my colleague ran it manually as himself (he is a local admin on the PC.)

I also know that the 1603 error the msi installer is throwing is a generic error code and usually isn't very informative or helpful by itself but closely examining the log I previously attached shows the "System.IO.FileNotFoundException: Could not load file or assembly 'System.Configuration..." error that I have been focusing on. In addition, the same log does not show any access denied errors when the MSI is as SYSTEM or as my colleague.

Any further thoughts or suggestions are welcome.

Thanks.

The same error happens whether it is run as a SCCM deployment or run manually as any local admin. It was initially rolled out via SCCM. Also I have come across two PCs with this exact same issue.

After more troubleshooting, I think there maybe more issues with these PCs than I thought. I tried to get to event viewer on both and I get error messages stating the MMC snap-in cannot be loaded. Trying to open other various snap-ins give the same error. To try and fix I have run the following

sfc /scannow
dism /Online /Cleanup-Image /CheckHealth
..net troubleshooting and repair tool
removed/reinstalled .net 3.5 and 4.6
reregistered all mof files in WMI

After performing all of the above the issues remain and I think we are at a point that both PCs need to be reimaged.