https://github.com/bitcoin/bitcoin/pull/19806/commits/f6e2da5fb7c6406c37612c838c998078ea8d2252
> Don't return null snapshotblockhash values to avoid caller complexity/confusion.
----
https://github.com/bitcoin/bitcoin/pull/21681/commits/931684b24a89aba884cb18c13fa67ccca339ee8c
> validation: fix ActivateSnapshot to use hardcoded nChainTx
>
> This fixes an oversight from the move of nChainTx from the user-supplied
> snapshot metadata into the hardcoded assumeutxo chainparams.
>
> Since the nChainTx is now unused in the metadata, it should be removed
> in a future commit.
----
https://github.com/bitcoin/bitcoin/pull/21681/commits/91d93aac4e3fe6fff5ef492ed152c4d8fa6f2672
> validation: remove nchaintx from assumeutxo metadata
>
> This value is no longer used and is instead specified statically
> in chainparams. This change means that previously generated
> snapshots will no longer be usable.
----
https://github.com/bitcoin/bitcoin/pull/21582/commits/fa9b74f5ea89624e052934c48391b5076a87ffef
> Fix assumeutxo crash due to missing base_blockhash
----
https://github.com/bitcoin/bitcoin/pull/21584/commits/fae33f98e6a8d5934edbdce2eb8688112eac41a8
> Fix assumeutxo crash due to invalid base_blockhash
>
> Can be reviewed with --color-moved=dimmed-zebra --color-moved-ws=ignore-all-space
This is a backport of [[https://github.com/bitcoin/bitcoin/pull/19806 | core#19806]] [5/8], core#21681 (partial), core#21582 (partial), core#21584 (partial) and core#21585
Notes:
- The test related changes from core#21681, core#21582, core#21584 and core#21585 are in D11241