We need a warning messages for invalid character filenames.

I am running into this a lot lately, as I share with PC and Mac users.

I now see constant sync errors with the latest Dropbox desktop app.

I'm even discovering many older files that never synced.

While it's great that there are links to take you to the offending files in the web UI, it would be even better if Mac users were initially alerted to this potential problem when syncing. How about something that pops up on a Mac along the lines of "Please note that if these folders/files are intended to be shared with Windows users, some of them contain characters which are not supported in Windows, and will prevent syncing...", etc., followed by a list of the folders/files in question.

I also agree that Dropbox should not automatically try to correct this, as many of the files in my case are resources referenced by other files, and changing the names would break things for everyone.

We have a mixed team of Apple Mac and Windows users. The Mac users are constantly forgetting to make sure that their filenames are Windows-compatible, resulting in a long list of sync errors which are tedious to correct manually.

Would it not be possible to have an option whereby Dropbox would refuse to upload files which have incompatible filenames, or at the very least alert the file's author/editor at the point the new or renamed file is uploaded?  As opposed to the present situation, where the Mac user responsible for the error doesn't get a warning at all, while Windows users get the sync errors and have to correct them!