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Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 12.0.2): 13.0.5
Operating system and version (eg, Ubuntu 17.04): Ubuntu 16.04 (Xenial)
Apache or nginx version (eg, Apache 2.4.25):
PHP version (eg, 7.1):
The issue you are facing: I am using Zorin (Ubuntu 16.04) and running V13.0.5 (just upgraded) today but was on 13.0.1. I have nextcloud sync on Linux as well as on Windows 10 (v2.3.3.1) and sharing the same drive (NTFS) and it never had an issue accessing files from both OS (Windows 10 and Zorin / Ubuntu). But very recently I noticed (not using Windows often until last week) and some of the files which are accessible on Ubuntu are not accessible on Windows 10 (same drive / folder / NTFS).
All the files are on Nextcloud server V13.0.1 / 13.0.5 were able to sync to Ubuntu / Zorin 16.04 if I re-sync (deselect and select) and also remove the folder. However when I did the same on Windows 10 (V2.3.3.1), it would only able to sync some files (mostly older files) and not able to sync the entire folder from Nextcloud server (Deselect folder and re-select). And if I sync via Linux first (which sync 100%) and reboot into Windows 10, I have many files showing yellow exclamation marks and when I access these files I get the follow error message - “The directory name is invalid”
Any suggestion and workaround solutions would be greatly appreciated.
Is this the first time you’ve seen this error? (Y/N):Yes
Steps to replicate it:
The output of your Nextcloud log in Admin > Logging:
PASTE HERE
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
PASTE HERE
The output of your Apache/nginx/system log in /var/log/____:
PASTE HERE