Quick answer: Unity Addressables Content Update rejecting an updated asset because the address conflicts with a renamed one? Stale entries in the content state need cleanup.
Renamed an asset address from 'sword_iron' to 'iron_sword'. Content Update fails: duplicate address sword_iron.
Regenerate content state
Build a fresh content state. Renamed entries replace old; conflicts resolved.
Or migrate the old address
For shipping projects, the old address may be in players' caches. Map old -> new in a redirect table.
Audit for duplicates
Tools to scan address spaces for duplicates. Surface at PR time; not at shipping.
“Addressables names are unique. Renames create transitional duplicates.”
Avoid renaming Addressables addresses post-launch. The migration cost is high; alternative addresses are usually fine.