Hi,

OpenUpgrade underwent a refactor after Odoo 8. In Odoo 9 and later, the correct import is:

        from openupgradelib import openupgrade

The suffix _90 was never part of the library -- sometimes older community migration scripts or experimental branches had references to it.

So, this happens if:

       You’re using a custom or outdated migration script written for an obsolete branch, or

       You mixed openupgradelib (modern package) with an old OpenUpgrade repository clone that references openupgrade_90.

Your OpenUpgrade repository matches the target version.

         For migration from 8.0 > 9.0:

         git clone https://github.com/OCA/OpenUpgrade.git -b 9.0 openupgrade-9 cd openupgrade-9

Hope it helps.