Could you specify that a bit? update from which version? (doesn't have to be precise, but did you update from 4.0.x or from a recent 5.0 version). What sort of data did you lose?
Zotero does not touch your data directory at all during regular updates, so likely something else is going on here.
Dear Adam I updated my MacBook Air from 4 till 5 as it told me I couldn't sync otherwise. After that I synced with my Mac which was already updated and the I discovered all my data of the last two months (more or less) were gone. Paul
Did the Mac have any of the newer data? Syncing for version 4 has been disabled for a while, so if you had the newer data on the macbook, that picked up an empty data directory on update and synced that, that'd explain what you're seeing.
Did you have the data on the laptop in a custom location?
Upgrade Storage
Zotero does not touch your data directory at all during regular updates, so likely something else is going on here.
I updated my MacBook Air from 4 till 5 as it told me I couldn't sync otherwise.
After that I synced with my Mac which was already updated and the I discovered all my data of the last two months (more or less) were gone.
Paul
Did you have the data on the laptop in a custom location?
Where would I find such a custom location?
https://www.zotero.org/support/kb/data_missing_after_zotero_5_upgrade
has instructions for your scenario
Paul