Fixing Thunderbird calendar modification failed repeated unspecific errors

As people who have screenshared with me may have noticed, but apparently i have not complained about yet here, Thunderbird Lightning calendar has been giving me repeated, utterly unspecified “modification failed” error messages with my NextCloud calendar for weeks now.

Following a ten-year-old post about the same generic “MODIFICATION_FAILED” with no detailed info on the problem messages for Google Calendar, i looked for a specific NextCloud plugin and found that there are a couple:

Seems to have fixed it so far.