UUM-128581

Fixed in 7000.0.0a16

Mentioned in 2 release notes.

First fixed in 7000.0.0a16 (Nov 5, 2026); relisted in 1 later release.

Open on Unity Issue Tracker
VersionSectionRiskImpactNote
7000.0.0a16Fixes
Prefabs
FixFixed an issue where "Assertion failed on expression: 'fidA != fidB'" was logged when entering Play Mode in a scene with a Prefab instance that has the same FileID as an object in its source Prefab, or when importing a corrupt Prefab with such a nested Prefab instance. Such Prefabs now fail to import with an error that identifies the affected object.
7000.0.0a16Fixes
Prefabs
FixFixed an issue where "Assertion failed on expression: 'fidA != fidB'" was logged when entering Play Mode in a scene with a Prefab instance that has the same FileID as an object in its source Prefab, or when importing a corrupt Prefab with such a nested Prefab instance. Such Prefabs now fail to import with an error that identifies the affected object.

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