Non ASCII characters prevent files from being synced

I’m trying to create a backup of important files from my Windows PC to a Raspberry Pi running Linux using Syncthing. Some files fail to sync without any error message or other information. They simply remain listed under “Out of Sync Items”. The files that fail to sync are those with non-ASCII characters in their filepath. When changing any one of these characters to an ASCII character, they are synced without a hitch.

When trying to solve the problem I found an old Support topic: Symbols & Non-English Alphabets in Filenames, however in that topic it was made clear that “every character in your files’ names must be a single unicode symbol, letter, or number”, the main problem in this topic was that some characters is actually two characters with the example of the character ‘Å’ sometimes being “Latin letter “A” and combining ring above “°””. After reading this, I checked the characters that where failing with unicodeplus.com however they seemed to be of the single character form. However, just to be sure, I pasted the correct single-character form into the file name to no avail. Besides, when copying the character shown in the file name inside the ‘Out of Sync Items’ in my RaspberryPi and pasting it into the aforementioned website, it successfully identifies that it is only one character. And since it doesn’t really matter what the file is actually called, if the receiving end says it is a valid single unicode character, then it shouldn’t run into a problem with it. I’m using v2.1.1, Windows (64-bit Intel/AMD) on my PC and v2.1.0, Linux (64-bit ARM Container) on the Raspberry Pi.

Gonna need more details. Screenshots, filenames, …

These are some of the files that won’t sync, all of the non-english characters are single unicode characters.

Some files fail to sync because their parent folder has a non-english character, this results is caused by syncthing failing to create the folder and there being unable to create any files in that folder

I hope this is what you need, thank you in advance.

What kind of filesystem are you using on the Pi?

Fascinating. That “invalid argument” is from the operating system, not Syncthing, so it is rejecting the names for some reason.

Thank you for asking that question, I had forgotten that when I first set up the RaspberryPi a couple years back, I used FAT32 since it was universally compatible and I thought that would be a usefull feature for this exact reason, it would make it possible to share files between any operating system. However FAT32 does not support Unicode since it is simply too old (Unicode did technically come first, but still). I updated the file system to ext4 and now everything works great. Thanks for the help!