Uncaught Error: Failed assertion: Invalid changeset (checkRep failed)

Hey guys. We are using stable and have the problem that some pads randomly stop working and throw an uncaught error in the console.

Uncaught Error: Failed assertion: Invalid changeset (checkRep failed) 

Example:

https://etherpad.tugraz.at/p/l3tsbet

When this happens, the “loading” overlay blocks any action. It’s unlikely to be a copy&paste issue because it sometimes happens to entirely handwritten pads.

An interesting thing is, that the timeslider (opened by appending /timeslider to the url) always works without problems.

https://etherpad.tugraz.at/p/l3tsbet/timeslider

Right now we are manually fixing the pads by exporting+importing with HTML (losing all changesets). Any idea whats wrong?

[JohnMcLear]

Dude, the error is in your log!

[2020-05-05 00:04:12.541] [ERROR] console - table is not configured with charset utf8 -- This may lead to crashes when certain characters are pasted in pads
[2020-05-05 00:04:12.543] [INFO] console - RowDataPacket { character_set_name: 'utf8mb4' } utf8

See: https://github.com/ether/etherpad-lite/issues/3959

[RalfJung]

Indeed doing the “replace ???? by ??” helped here as well. 😃 Seems like the last changeset was someone inserting an emoji (it ended in $????).

However, I do not understand why this is classified as a “minor bug”. This bug leads to total loss of a pad (until someone notices the /timeslider thing, which took a week in our case, and even then history is lost).