You may see this error if you are viewing a dashboard that references tiles found in a dashboard pack that you do not have installed.
The <Tile name> tile could not be found, you may be missing a dashboard pack.
This can occur if a dashboard pack is missing.
To fix this issue, install the missing dashboard pack from the SquaredUp right-hand menu ☰ > Import dashboard packs page and the error should disappear.
If it does not disappear immediately, you may need to reload dashboard packs.