Colour dialog box error

On one of my apps the colour dialog box does not load. It comes up with an error. This was working a couple of weeks ago, but now I cannot change any colours on any element.
. Other apps okay
. New elements in same app have same error
. New apps, ,no problem.
Just seems to be some sort of corruption with this one app (and its backups)
Help please.

what about revealing, which error exactly you get?

It would really help if you provided a screenshot of your relevant blocks, so we can see what you are trying to do, and where the problem may be.

To get an image of your blocks, right click in the Blocks Editor and select “Download Blocks as Image”. You might want to use an image editor to crop etc. if required. Then post it here in the community.