User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/109.0

Steps to reproduce:

I right-clicked on an email, selected Convert To -> Event and then filled in the data and pressed ok.

Actual results:

My CalDAV server rejected it with an error. I thought it was an issue with my CalDAV server (Seafile) and reported it there but they pointed me to the ICS validator which showed that the resulting VCALENDAR iCal ics file did have blank lines in it, which is not addressed by RFC 5545.

This issue causes this error: https://github.com/Kozea/Radicale/issues/1274

Sending the thunderbird-generated VCALENDAR data into the validator at https://icalendar.org/validator.html#results gives warnings:

Blank line detected, specification does not address the use of blank lines near line # 61
Line length should not be longer than 75 characters near line # 142Reference: RFC 5545 3.1. Content Lines
Line length should not be longer than 75 characters near line # 145Reference: RFC 

Expected results:

The VCALENDAR data should have been generated with no blank lines so that the validator would pass so that downstream users of the data would work as expected.

*correction, my server is radicale, not Seafile.

See also bug 1776462

Ah yes and that one actually pointed me to bug 1738611 which this really is a pure dupe of. I will close this as a dupe.