Error 3045 Could not use ... File already in use

UPDATE 12/20/2021
Microsoft has posted a fix for this issue.
They also write that the fix may not be applied automatically but include a link to Install Office Updates manually. 
UPDATE 12/16/2021
Microsoft Support documents this issue and gives specifics on other versions of Office.
UPDATE 12/15/2021
Microsoft has acknowledged the issue and is working on a fix.
This error affects users who are using CMS on multiple computers over a network and just started happening 12/14/2021.
It has been determined that an update by Microsoft released as part of "Patch Tuesday" (second Tuesday of each month) is the cause of this issue.
Until Microsoft fixes this issue, the only option is to remove this update on each computer using CMS.
Specifically, you're looking for the update known as KB5002099.
Below are the steps to remove it.
Note: These steps and screenshots are for Office 2016 msi type installation. If you have a "Click-To-Run" type of installation (Microsoft 365 or Office 2019 via Tech Soup for example), please follow instructions here
  1. Exit all office applications (Word, Excel, Access etc.)
  2. Click Start and type "Control Panel"

  3. In the Control Panel Click Programs then click View Installed Programs

  4. Search for KB5002099. Right click it and choose Uninstall.

You don't need to remove any of the other updates that were installed on that day, just the KB5002099 update.