I send out the Wikimedia Highlights blog post every month. This month I ran into a strange error.
Specifically - I previewed my notification on Special:NotifyTranslators. Everything was okay so I clicked send. After a few seconds I got this message (below):
Database Error: To avoid creating high replication lag, this transaction was aborted because the write duration (6.9671151638031) exceeded the 6 seconds limit.
If you are changing many items at once, try doing multiple smaller operations instead.
However, the notification tool sent out an email shortly after the error message appeared.
There is no log entry for this - https://meta.wikimedia.org/w/index.php?title=Special%3ALog&type=notifytranslators&user=&page=&year=&month=-1&tagfilter=
Any questions feel free to ask.
Edit (adding links): https://meta.wikimedia.org/wiki/Wikimedia_Highlights,_January_2016