I have a Ubuntu(with KDE) desktop as a samba server, my iPad can view and edit the shared files. But can't upload files properly. But it uploads only when files are put in a folder and upload the whole folder. Edit: Added screen shots
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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
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To add more info then the other comments, this error message seems to indicate that the name of the file is too long or contains invalid characters. In your case, that might be the ".pages.pdf" (the double dots) I would personally try to write only ".pdf".
After a bit of googling, it seems that another reason might be that Apple be Apple. In other words, there seems to be a long, unresolved bug with the smb client in the native apps that bugs out when the smb server is on Linux (and sometimes even if it's on Windows...). One of the solutions mentioned was to use another file manager app.
Now, I do get that, sometimes, error messages are very useless (looking at you "An error occurred"...), but this one is actually pretty self explanatory... A bit of googling before just posting about your problem. And another thing that's generally appreciated is to write what you tried to do to solve the problem. And btw, this doesn't seem to be a Linux problem, more of an Apple one, so you should post it on that Community instead of c/Linux.