Anyone else seeing this? Tags with "foo:bar" syntax changed by iCloud to "foo/bar" syntax

I thought this was a DEVONthink issue, but it now seems to be an iCloud issue. I’m getting very strange behavior in tagging, and it seems to have started recently: tags with “foo:bar” syntax are being changed by iCloud to “foo/bar” syntax – which get converted in DEVONthink to nested tags.

Here’s a sample of what’s being changed (only on files in iCloud):

The full story is on the DEVONthink forum:


‘:’ is not allowed in filenames and folder names on macOS. This behaviour is probably related to that.

Forward slash (‘/’) is also best avoided for compatibility reasons. While it will work in filenames and folder names on macOS, it won’t on other UNIX-style operating systems, and is also a prohibited character on a number of cloud storage systems (M365 OneDrive, for example).


Thanks, Dario, but my issue is with tags, which do allow the : (colon), and which I’ve been using for years, partly at the recommendation of the very tech-savvy Brett Terpstra. And the problem is that iCloud is ITSELF introducing the slash syntax. In fact, as soon as I apply an existing tag with a colon (e.g., “foo:bar”), I can watch in Finder as the tag is changed to “foo/bar”.

I know, but it could be related. A quick search reveals others have also reported issues with using colons in tags:


Just because something is permitted does not mean it is recommended (with apologies to Brett).

Software Engineering Stack Exchange

I think everyone knows about the Robustness Principle, usually summed up by Postel’s Law:

Be conservative in what you send; be liberal in what you accept.


Thanks for the link. I’m usually very impressed with the Electric Light Company, but I think I dismissed that post when I saw it. Only 7 Finder Tags? For real? Don’t most Mac Power Users use at least 50? I’m now utterly confused. I’ve been using them for years, and sure, it has often seems that macOS has been a bit clumsy with tags – not to mention their absence from iOS and iPadOS, but there are dozens of apps catering to managing a complex system of tagging. Now I don’t know what to believe!