There are few end-users reports about database corruption when validation put in firebird.log following message(s):

Error: Data page 195225 {sequence 57} marked as secondary but contains primary record versions in table

Nobody can reproduce it so far. The bug is very rare, there was just a few reports since release of FB3.
The visible effect is that some records is not accessible with natural scan of table, but could be found
using indexed access.

This ticket created to test possible regressions of the patch that should resolve the issue.

It might be related to CORE-5459 (#5730)