SUMMARY

STEPS TO REPRODUCE
1. Clear akonadi cache on a mail folder
2. akonadictl restart
3. Observe konsole output

OBSERVED RESULT
ProtocolException thrown:Failed to write data to stream
Qt has caught an exception thrown from an event handler. Throwing
exceptions from an event handler is not supported in Qt.
You must not let any exception whatsoever propagate through Qt code.
If that is not possible, in Qt 5 you must at least reimplement
QCoreApplication::notify() and catch all exceptions there.

terminate called after throwing an instance of 'Akonadi::ProtocolException'
  what():  Failed to write data to stream

EXPECTED RESULT


SOFTWARE/OS VERSIONS
Windows: 
MacOS: 
Linux/KDE Plasma: 
(available in About System) - What is About System?

KDE Plasma Version: 5.53.0
KDE Frameworks Version: 5.53.0
Qt Version: 5.11.3 (built against 5.11.3)

ADDITIONAL INFORMATION

I've only seen this once, and I can't tell what process caused it.