Block filter index corruption post reorg and unclean shutdown #34261

1. 
   dergoegge commented at 11:36 am on January 12, 2026: member

   The block filter index may be left in a corrupted state, preventing the node from restarting (without reindexing), after a series of specific events:

   1. Clean shutdown
   2. Restart combined with an immediate reorg of the previously stored best chain tip
   3. Unclean shutdown after reorg takes place (before chainstate flush)
   4. Restart, leading to the following

   0[        62.579] [               node2] [inf] 2026-01-10T16:58:52Z [all:error] previous block header belongs to unexpected block 44ee2f358de32719802fe11d3985af7a0f9077b90ee5ca16c42f7278a8d89a50; expected 532c10b42179b4f3f5a41f9990108a63bcd7021dd02ba6997f5ff3375d297676
   1[        62.579] [               node2] [inf] 2026-01-10T16:58:52Z [all:error] Cannot read last block filter header; index may be corrupted
   

   See attached debug log for an example of this happening.

   blockfilter_corruption.log

   This was found with a test running on Antithesis.

2. maflcko added the label UTXO Db and Indexes on Jan 12, 2026
3. maflcko added the label Data corruption on Jan 12, 2026
4. 
   mzumsande commented at 1:29 pm on January 12, 2026: contributor

   Looks very similar to #33208 / #33212#pullrequestreview-3140857089 . I did some work on a fix for that in fall (making sure that we never commit an index ahead of the flushed chainstate) but there were some complications with my approach and I never PR’ed it.

Contributors
dergoegge mzumsande

Labels
UTXO Db and Indexes Data corruption