The connection configuration "operation_timeout_ms" is now deprecated. The option is still accepted in this version but will have no effect when set.
The connection configuration "failpoint_eviction_fail_after_reconciliation" has been replaced by "failpoint_eviction_split".
The cursor configuration "prefix_search" is now deprecated. The option is still accepted in this version but will have no effect when set. Users should look into the new bound cursor interface.
The session API "flush_tier" function is removed. Users of this function should move to calling "checkpoint" with the "flush_tier" configuration specified.
The connection configuration "debug_mode" (only used for testing) has had its "flush_checkpoint" option removed.
The connection configuration "timing_stress_for_test" (only used for testing) has had its "checkpoint_evict_page" option removed.
The verbose messaging system has had its range of debug options extended. The previous "DEBUG" level now maps to "DEBUG_1", and will output significantly fewer messages. If you want all of the same messages as the old "DEBUG" level, you'll need to use "DEBUG_5".
The WiredTiger 11.0 release is a complete refresh of the WiredTiger storage engine. Applications written to earlier versions of the WiredTiger API will require review (although the API structure is substantially the same as previous releases). Applications using row-store data objects can use those objects without change. Applications using fixed- or variable-length column-store data objects will require a dump and reload cycle to import those objects into a 11.0 release environment.
Please refer to the following link for upgrade suggestions for version older than 11.0.0. https://source.wiredtiger.com/10.0.0/upgrading.html