KeyError: 'tree' on webclient_rendering_context after migrating from Odoo 17 → 18 CE with OpenUpgrade 18

[inaris-tech]

Hello !

We’ve migrated our production database (inaris_mig) from Odoo 17 CE to Odoo 18 CE using the OCA/OpenUpgrade 18 scripts. The migration finishes without critical errors, but when accessing the web UI we keep getting:

KeyError: 'tree' File ".../web/models/ir_ui_view.py", line 14, in get_view_info 'icon': _view_info[type_]['icon'], ~~~~~~~~~~^^^^^^^ KeyError: 'tree'

We have tried:

Converting all mode = 'tree' → mode = 'list' in ir_ui_view.
Replacing → in both arch_db and arch_fs (ir_ui_view).
Grepping+fixing every in our custom‑addons and core addons XML.
Cleaning up JSON/XML in the database and forcing view reloads.
Disabling all leftover modules still at v17.

Environment

OS: Ubuntu 24.04
PostgreSQL: 16
Python: 3.12.3 (venv)
Odoo: CE 18.0 (official Git branch 18.0)
OpenUpgrade: OCA/OpenUpgrade 18.0
Service: systemd unit running as user odoo18

2025-07-20 14:20:15,885 177772 ERROR inaris_mig18 odoo.http: Exception during request handling. ... File "/opt/odoo18/odoo/addons/web/models/ir_ui_view.py", line 14, in get_view_info 'icon': _view_info[type_]['icon'], ~~~~~~~~~~^^^^^^^ KeyError: 'tree'

Has anyone encountered a similar persistent KeyError: 'tree' on Odoo 18 after migration?

Is there a known, “supported” way to force Odoo’s core to recognize the old tree view type (without hacking every XML or manually updating every database view)?

Thanks :)

[pedrobaeza]

It seems you have some manual/old actions with tree value.