A copy-on-write view freezes the structure of the module view it was copied
from. When that module view changes mode between two versions, the copy keeps
an arch written for the old mode and the upgrade dies on
« Element ... cannot be located in parent view », hours into the migration.
Measured on a real 12.0 database: portal.frontend_layout is declared primary in
12.0 (full QWeb template, so a full-template arch is legitimate) and becomes an
extension in 13.0 (inherit_id + xpath). The 2021 COW copy follows the module,
turns into an extension, and keeps its 12.0 arch. The customization is genuine;
the breakage is produced by the migration.
check_cow_views.py compares the mode stored in database with the mode declared
in the target version sources and sorts the views in three buckets: at risk
(mode change), module absent from the target version, and pages made from the
editor (not at risk). Read-only, and called from step 2 so the list is known
before the long version loop rather than during it.
On the reference database it reports exactly the view that broke the upgrade,
plus 7 views whose module is gone in 13.0 (custom theme included).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Mathieu Benoit
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