"The folder you tried to unselect contains the windows documents folder, which is an important folder in windows and is currently pointed to Onedrive"

I'm genuinely horrified by this answer

I am also now having the same and other bizarre behavior with One Drive! I am simply using OD to store my phone's pics/vids (S23 Ultra), and to save space I do not store them on the phone. I occasionally manually download the phone's pics/vids stored on OD to my PC (zip files... it's the only way with OD!) for archival backup. My PC had nothing to do with syncing/storing my phones pics/vids... until NOW! I was backing up my data partition (straight file copy) to an external SSD and I noticed Directory Opus (my file manager) showed that it was downloading and copying my One Drive phone pics/vids!!! WTH? I don't have the space on either the data partition OR the SSD drive to download all these pics/vids and I do not want ANOTHER damn copy of them to eventually wind up mismanaging with the convoluted OD processes and accidentally deleting them all!!! Upon trying to stop these files from being downloaded, I ran into the same issues you did. I am unable to NOT include the folders from syncing. I get the Documents folder contains important... ...isn't supported for file backup" Seems irrelevant, as I'm not trying to sync/backup my Documents from my PC, but it seems to be tied to the error. This is absolutely bonkers and unexpected (and unusable) behavior from One Drive. All I am able to do is to completely uninstall One Drive from my PC until I can determine WTAH this product is doing. It shouldn't be this hard. [Retired IT Ops Director]

Thanks, but the frustration we're facing is no longer the bug itself, but why Microsoft engineers messed up OneDrive so that users have to waste time fixing it.

We know how to fix this bug, but we still can't fix the management issues with the engineering team.

These are the options I see under Manage backup - not sure what to do here. Most files are under Documents, but I don't want to toggle that, afraid of what might happen.

Migrating to another drive or external drive is not an option - that's all been locked down.

Did you read the question? Please read the question first before replying.

Here it is again in case you didnt see it the first time:

When I try to unsync any folder, this error message appears:

"The folder you tried to unselect contains the windows documents folder, which is an important folder in windows and is currently pointed to Onedrive"

This is a new thing that started happening over the weekend, as I use OneDrive on a daily basis.

Rebuilding all the folders and subdirectories are not an option since they are time-consuming and there is not enough space on my local drive (which is why I am using OneDrive and turning folders on and off).

Microsoft, please sort this out.

Are you talking about the Choose folders window where you check or uncheck the folders you want to sync to your computer?

The Manage backup window is where you choose the folders that you want to sync to OneDrive.

They both use the word sync in their descriptions but they have different functions.

                                                      **Manage backup**

If you are running out of storage space on your PC then I suggest you use the Files On-Demand feature of OneDrive:

See the video here: https://support.microsoft.com/en-us/office/sync-files-with-onedrive-files-on-demand-62e8d748-7877-420f-b600-24b56562aa70