I have tried several versions 4.x.x (both 32 and 64 bit) in Windows 10, including the most recent 4.3.1, but I never got the file links working as they should:
F7 does not find the file related to the current entry.
Ctrl + Shift + F7 searches for a very long time but does not find any links. (Apparently it also keeps running after closing the program, because I had to kill two instances of the JabRef.exe process using task manager in order to be able to uninstall the program.)
Each time I have had to return to 3.8.2. This is quite annoying, because if I saved the database in 4.x.x, the group tree is gone in 3.8.2 and I have to restore the database from a backup.
Any suggestions how to make it work?
The format of the file pattern changed in 4.x (its now the same as the BibTeX key pattern). Simple patterns are automatically converted to the new format, but for more complicated patterns the auto-migration sometimes fails. This is probably the case for you and you need to manually adapt the pattern in the preferences.
I have not used any pattern, as all file names start with the BibTeX key. In 3.8.2 linking works with the following two options selected:
Use the BIB file location as primary file directory
Autolink files with names starting with the BibTeX key
In database properties, the general file directory is “.”. The files are in subfolders in the same folder as the BIB file.
Ok, then this sounds like a bug (probably due to the fact that your files are in a subfolder). Can you please open a bug report at https://github.com/JabRef/jabref/issues. Thanks!