OneDrive has a limitation whereby it cannot sync a path longer than 255 characters, and additionally it will not accept files with the following characters in the path:

/ \ > < : * " ? |


It won’t accept a space at the start or end of a filename, or a dot on the end of a filename. These are quite annoying if you’re using a Mac, as none of those restrictions apply to MacOS! I recently put this script together in PHP to resolve hundreds of such issues with a large structure of folders I wanted to backup. Doing it by hand would take hours, so I needed an automated fix.

Please note: the content above is an image due to a problem with WordPress rendering it correctly! Here, as an attachment, is the PHP file: fix_onedrive.php

If you have a lot of folders to fix, you can call this recursively easily from the command line (ie. Terminal). Just save the script to a PHP file (I use fix_onedrive.php) and set the execution bits (chmod +x fix_onedrive.php). Then you can use the standard Unix find command to call this script over every folder:

find PATH_TO_ONEDRIVE -type d -exec ./fix_onedrive.php {} ';'


I am sure that a neater script – possibly even doing everything in AppleScript – would be effective, but since this worked for me and the only other fixes I saw cost nearly $200, I thought I’d better post it. Lastly, I must say I find it incredible that these restrictions exist in the first place, and hope that Microsoft are aware that they pose a significant barrier to those of us wanting to use OneDrive. Let’s hope it can be resolved properly in an update.