When they introduced IE7, they broke ClickOnce launchers all around the globe due to the new download prompting. I raised a defect with my MS Partner support dude and normal MS support. All they managed was a registry fix shipped out to turn an old flag on that was removed from the UI but was still in the code inside IE. I did the diagnostic work to get that far.
After arguing for months with various support people at Microsoft I managed to get hold of people on both the IE and CLR teams and they both pointed at each other and refused to fix anything blaming the other team.
They called me every 6 months to ask me to close the ticket and I denied it because it wasn't fucking fixed. Eventually they stopped calling when Microsoft Connect was shut down. I wonder how many millions of issues they solved at that time!
Oh no wait, the issue still exists in IE11. They fixed it in old Edge.
This was a manual registry fix we had to deploy to 20,000 users at over 500 companies for 10 years.
Eventually we rewrote the software so it didn't use ClickOnce, instead passing context to the application via a shell protocol handler (much like Slack does).
Incidentally we're no longer an MS Gold partner and have no certified staff any more. This is not a coincidence. They did a shitty job and like hell we were paying any further. Amazon got our business in the end.
The issue?
You can't set window.location.href=""; to a clickonce activation link because of a race condition in the download bar in IE.