QuickBooks Migration Guide
Upgrading to 4.0.0
The config no longer has a nested credentials field, while the config fields remain the same, they are now at the root level instead of being nested inside a credentials object. This is done to fix the refresh token issue where it wasn't getting updated after 24 hours.
4.0.0 shipped without a config migration, so connections created before it had to have their config fields repopulated by hand. Since 4.2.0 the connector migrates a nested credentials config to the root-level fields on its own and persists the result, so no manual repopulation is needed.
Upgrading to 3.0.0
Some fields in bills, credit_memos, items, refund_receipts, and sales_receipts streams have been changed from integer to number to fix normalization. You may need to refresh the connection schema for those streams (skipping the reset), and running a sync. Alternatively, you can just run a reset.