We are having this issue with Civil 3D 2016.
The message again was:
You have e:\ACADBackups\C3D2016\blah.bak open. This file must be saved to complete the addition of page overrides for the sheet set.
It is related to the movebak command. We ran the movebak command to save the files to a folder on the local E: drive. E:\ACADBackups\C3D2016. Notice no spaces, per:
https://knowledge.autodesk.com/support/autocad/troubleshooting/caas/sfdcarticles/sfdcarticles/Unders...
When the "Movebak ." command was run, resetting the bak files to save to their default location(where the master file resides), the error message went away. However, we would like the Movebak command to save to the local hard drive without issue. This does work in 2013 and 2015 we only see the issue in 2016. Is this something that could be addressed? It would help save network bandwidth, declutter the file server and save its storage space as well.
Thank you for your assistance.