I have had this error since I updated my OS to KDE Neon newest version (built on Ubuntu 18.04), I tried reproducing it with a fresh file but couldn't do it. I couldn't reproduce with just a few tasks exported from my main file, only with my main. Maybe there's some time-out, I dunno, the updating is slow.
The result is: I try to update the top level recurring task of a set of nested tasks that all have planned start times. Only some of them get updated. I see some patterns as to which, but it's confusing. Some get updated to the current time, some recur correctly, and some seem unchanged. Very frustrating. Then, I can't successfully edit the dates in bulk either. I edit a bunch and only some or just one actually gets updated. So, fixing my tasks after this happens is a real pain.
Attached is a log file.
Just now, similar error with a task that had no children. It updated the planned and due dates correctly but failed to clear the actual-start date.
related maybe (but needs to be addressed either way) additional error report attached
Attaching another log of the same bug. Reliably happening now.
Another one after trying to edit all the dates in bulk in order to undo the first error (this is really painful and tedious)
I don't know if related to the bug, but it's extra hard to fix afterward because even though 100% of selected tasks have the same planned-start, it doesn't show as checked when doing a bulk edit, so when I check "planned start" it inserts the current date and time (and often fails to update everything).
It seems related to task-file size, probably something is timing out. If I save separately just the tasks in question, I can update that smaller file without problems.
In case it helps, attaching an anonymized copy of my file. Try completing the parent top-level task that has the life-preserver icon. On my computer, it fails to update all the child tasks and produces the error logs I shared earlier.
The new test with 8022 version makes this half-megabyte error log (attached) even though the dates update successfully.
Clarification, I get this error without doing any actions, just opening and closing Task Coach. Even with just a small example file. The error log is smaller then. (attached)
The latest fixes in the pre-release code seem to have solved this for me! Thanks!!