At a customers site there is an old Network with Exchange 2016 and a new Network with a fresh Exchange 2016 installation. There was a planned move last weekend. Using the old network outlook most of the times threw random messages at start like
"Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The operation failed."
or similar. There are like 4 different messages popping up. This problem exists for like 2 weeks now. You'd have to have a huge amount of luck to open.
This weekend I moved all the mailboxes over to the new network as planned. This was not the reason for the move but I hoped the problem would go away after the move. The problem now appears on the new network, too.
Most of the solutions I find online is because of damaged windows or outlook profiles. I would exclude this as the users got completely new profiles in windows and outlook is clean as well.
I've been searching for a solution for hours now.
I tried every solution provided I found online regarding windows and outlook profiles. I optimized the ESXi and Windows Server VM / Exchange performance as far as I could as I thought some timeout might cause this and as far as I knew what to do.
The problem exists >90% of the time starting outlook. When the Exchange is just rebooted and I start outlook on one of the client PCs it mostly works but if I close it again and start it again the error comes back.
Outlook is using a non-cached profile.
Network seems to have no losses. Server is a little bit too slow I think but this should not cause problems IMHO.
All of the clients have this issue since 2 weeks now. Customers comment: "We didn't do anything".
I have no idea what to look for and would like to request your help / ideas.