
This information comes from the Tryton migration. You should check the latest updates :
+ https://discuss.tryton.org/t/migration-from-4-6-to-4-8/440
+ https://discuss.tryton.org/t/migration-from-4-8-to-5-0


BEFORE THE UPGRADE:

1) Assign rules linked to users to a group (must be done before update).

2) Check taxes and tax codes definitions (inactivate old children taxes and add them to the right codes)

3) Before update, set an accounting category to all products which have accounts and taxes defined (see issue3805 )

4) Execute the script "before.sql"

5) update tryton server (./trytond --all)

AFTER THE UPGRADE:

1) Execute the script "after.sql"

2) synchronize records from Administration > Models > Models > Data

3) You should create the WriteOff Methods and Payment Methods to override the cash journals used for invoice payments and writeoff journals used for writeoff reconciliation. (see Tryton issue7450)
