Is this frontend or backend issue?

I didn't investigate much further, I think there is some issue with the statistics returned from the backend, there is some value KeyCount, which is normally a number and in this case is missing. For other batch operations it seems to be there, but not for this one. Can be fixed on the FE, but would be nice if it would behave consistently.

I'll look into that 🙂

@stepan662 can you please help me with reproducing this bug. Thanks:)

It happens when the batch operation adds 0 tags (can happen if the keys are already tagged with the same tag)

@JanCizmar, @stepan662 Is it okay if I just throw an exception when adding a tag to 0 keys? Or is this a useful feature (idk why)?

No, we shouldn't throw any errors, it's a valid case that can happen. We might skip activity creation all together (as basically nothing changed). But maybe we should tell the user how many keys were actually updated - however if this is complicated, I think it's enough to just not to create activity.