Thanks for letting us know. @625alex and I have reports of this error from a few users, but not very many, so we are having difficulty pinning it down.
You can send a note, please, to: Support@SmartTiles.click so we don’t clutter the Topic with personal debugging steps.
If you know how to use SmartThings API/IDE Live Logging some of that output may give you or us vital clues. Start Live Logging just prior to the actions that cause the error message… etc. Similarly, and Firebug or Chrome Debugger output can be helpful.
But in the meantime, feel welcome to experiment by using one of the additional child dashboards with zero device tiles (i.e., just the default tiles), and/or no temperature based tiles, no weather tile, … i.e., a few simple combinations to see if you find that any particular ones work and which ones don’t.