We recently migrated a bunch of users from one domain to another after two companies merged.
Everything went smoothly and users were able to work with little to no downtime.
However the migrated users started complaining that they were unable to open their Office Applications with the following error
Error code: 80090016
Correlation id: ********-cbe3-*****-9324-***********
Timestamp: 2020-01-16T16:52:10Z
Server message: Keyset does not exist Keyset does not exist.”
Some digging around we found the solution that worked for all our users
Go to the “C:\users\%username%\AppData\Local\Packages\” and rename the “Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy” folder to anything else for example”Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy.old”
After this try to open any Microsoft 365 app and log in again.
