Had the similar problem after upgrade from 20.12.5.14

```
[ch-01] 2021.02.24 20:31:13.845342 [ 17553 ] <Fatal> BaseDaemon: ########################################
[ch-01] 2021.02.24 20:31:13.845469 [ 17553 ] <Fatal> BaseDaemon: (version 21.2.4.6 (official build), build id: 6E2E926515F53BCF094B3D6BD7E9EB65BC5BCE6B) (from thread 10568) (query_id: b03fb6ff-7fe1-400e-bb55-d71b0c611525) Received signal Segmentation fault (11)
[ch-01] 2021.02.24 20:31:13.845530 [ 17553 ] <Fatal> BaseDaemon: Address: 0x90 Access: read. Address not mapped to object.
[ch-01] 2021.02.24 20:31:13.845583 [ 17553 ] <Fatal> BaseDaemon: Stack trace: 0xf518654 0xf518379 0xf525f05 0xf526640 0xe6ad857 0xf63b0ac 0xf63b879 0xf63b14c 0xf63b879 0xf63b14c 0xf63b839 0xf63ed80 0xf6432b6 0x84f6e4f 0x84fa8e3 0x7f6e6c5c9ea5 0x7f6e6c2f28dd
[ch-01] 2021.02.24 20:31:13.845660 [ 17553 ] <Fatal> BaseDaemon: 2. ? @ 0xf518654 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.845763 [ 17553 ] <Fatal> BaseDaemon: 3. DB::Connection::receivePacket(std::__1::function<void (Poco::Net::Socket&)>) @ 0xf518379 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.845821 [ 17553 ] <Fatal> BaseDaemon: 4. DB::MultiplexedConnections::receivePacketUnlocked(std::__1::function<void (Poco::Net::Socket&)>) @ 0xf525f05 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.845886 [ 17553 ] <Fatal> BaseDaemon: 5. DB::MultiplexedConnections::drain() @ 0xf526640 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.845969 [ 17553 ] <Fatal> BaseDaemon: 6. DB::RemoteQueryExecutor::finish(std::__1::unique_ptr<DB::RemoteQueryExecutorReadContext, std::__1::default_delete<DB::RemoteQueryExecutorReadContext> >*) @ 0xe6ad857 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846067 [ 17553 ] <Fatal> BaseDaemon: 7. DB::PipelineExecutor::tryAddProcessorToStackIfUpdated(DB::ExecutingGraph::Edge&, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, unsigned long) @ 0xf63b0ac in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846135 [ 17553 ] <Fatal> BaseDaemon: 8. DB::PipelineExecutor::prepareProcessor(unsigned long, unsigned long, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, std::__1::unique_lock<std::__1::mutex>) @ 0xf63b879 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846180 [ 17553 ] <Fatal> BaseDaemon: 9. DB::PipelineExecutor::tryAddProcessorToStackIfUpdated(DB::ExecutingGraph::Edge&, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, unsigned long) @ 0xf63b14c in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846241 [ 17553 ] <Fatal> BaseDaemon: 10. DB::PipelineExecutor::prepareProcessor(unsigned long, unsigned long, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, std::__1::unique_lock<std::__1::mutex>) @ 0xf63b879 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846308 [ 17553 ] <Fatal> BaseDaemon: 11. DB::PipelineExecutor::tryAddProcessorToStackIfUpdated(DB::ExecutingGraph::Edge&, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, unsigned long) @ 0xf63b14c in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846369 [ 17553 ] <Fatal> BaseDaemon: 12. DB::PipelineExecutor::prepareProcessor(unsigned long, unsigned long, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, std::__1::queue<DB::ExecutingGraph::Node*, std::__1::deque<DB::ExecutingGraph::Node*, std::__1::allocator<DB::ExecutingGraph::Node*> > >&, std::__1::unique_lock<std::__1::mutex>) @ 0xf63b839 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846439 [ 17553 ] <Fatal> BaseDaemon: 13. DB::PipelineExecutor::executeStepImpl(unsigned long, unsigned long, std::__1::atomic<bool>*) @ 0xf63ed80 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846485 [ 17553 ] <Fatal> BaseDaemon: 14. ? @ 0xf6432b6 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846562 [ 17553 ] <Fatal> BaseDaemon: 15. ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>) @ 0x84f6e4f in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846622 [ 17553 ] <Fatal> BaseDaemon: 16. ? @ 0x84fa8e3 in /usr/bin/clickhouse
[ch-01] 2021.02.24 20:31:13.846708 [ 17553 ] <Fatal> BaseDaemon: 17. start_thread @ 0x7ea5 in /usr/lib64/libpthread-2.17.so
[ch-01] 2021.02.24 20:31:13.846796 [ 17553 ] <Fatal> BaseDaemon: 18. __clone @ 0xfe8dd in /usr/lib64/libc-2.17.so
[ch-01] 2021.02.24 20:31:14.053143 [ 17553 ] <Fatal> BaseDaemon: Checksum of the binary: 88E22F0584BA91872F2E9BE493E6985B, integrity check passed.
```

_Originally posted by @chyy in https://github.com/ClickHouse/ClickHouse/issues/8997#issuecomment-785538830_
M(UInt64, group_by_two_level_threshold, 100000, "From what number of keys, a two-level aggregation starts. 0 - the threshold is not set.", 0) \
    M(UInt64, group_by_two_level_threshold_bytes, 100000000, "From what size of the aggregation state in bytes, a two-level aggregation begins to be used. 0 - the threshold is not set. Two-level aggregation is used when at least one of the thresholds is triggered.", 0) \
    M(Bool, distributed_aggregation_memory_efficient, true, "Is the memory-saving mode of distributed aggregation enabled.", 0) \
    M(UInt64, aggregation_memory_efficient_merge_threads, 0, "Number of threads to use for merge intermediate aggregation results in memory efficient mode. When bigger, then more memory is consumed. 0 means - same as 'max_threads'.", 0) \
    \
    M(UInt64, max_parallel_replicas, 1, "The maximum number of replicas of each shard used when the query is executed. For consistency (to get different parts of the same partition), this option only works for the specified sampling key. The lag of the replicas is not controlled.", 0) \
    M(UInt64, parallel_replicas_count, 0, "", 0) \
    M(UInt64, parallel_replica_offset, 0, "", 0) \
    \
    M(Bool, skip_unavailable_shards, false, "If 1, ClickHouse silently skips unavailable shards and nodes unresolvable through DNS. Shard is marked as unavailable when none of the replicas can be reached.", 0) \
    \
    M(UInt64, parallel_distributed_insert_select, 0, "Process distributed INSERT SELECT query in the same cluster on local tables on every shard, if 1 SELECT is executed on each shard, if 2 SELECT and INSERT is executed on each shard", 0) \
    M(UInt64, distributed_group_by_no_merge, 0, "If 1, Do not merge aggregation states from different servers for distributed query processing - in case it is for certain that there are different keys on different shards. If 2 - same as 1 but also apply ORDER BY and LIMIT stages", 0) \
    M(Bool, optimize_distributed_group_by_sharding_key, false, "Optimize GROUP BY sharding_key queries (by avoiding costly aggregation on the initiator server).", 0) \
    M(UInt64, optimize_skip_unused_shards_limit, 1000, "Limit for number of sharding key values, turns off optimize_skip_unused_shards if the limit is reached", 0) \
    M(Bool, optimize_skip_unused_shards, false, "Assumes that data is distributed by sharding_key. Optimization to skip unused shards if SELECT query filters by sharding_key.", 0) \
    M(Bool, optimize_skip_unused_shards_rewrite_in, true, "Rewrite IN in query for remote shards to exclude values that does not belong to the shard (requires optimize_skip_unused_shards)", 0) \
    M(Bool, allow_nondeterministic_optimize_skip_unused_shards, false, "Allow non-deterministic functions (includes dictGet) in sharding_key for optimize_skip_unused_shards", 0) \
    M(UInt64, force_optimize_skip_unused_shards, 0, "Throw an exception if unused shards cannot be skipped (1 - throw only if the table has the sharding key, 2 - always throw.", 0) \
    M(UInt64, optimize_skip_unused_shards_nesting, 0, "Same as optimize_skip_unused_shards, but accept nesting level until which it will work.", 0) \
    M(UInt64, force_optimize_skip_unused_shards_nesting, 0, "Same as force_optimize_skip_unused_shards, but accept nesting level until which it will work.", 0) \
    \
    M(Bool, input_format_parallel_parsing, true, "Enable parallel parsing for some data formats.", 0) \
    M(UInt64, min_chunk_bytes_for_parallel_parsing, (10 * 1024 * 1024), "The minimum chunk size in bytes, which each thread will parse in parallel.", 0) \
    M(Bool, output_format_parallel_formatting, true, "Enable parallel formatting for some data formats.", 0) \
    \
    M(UInt64, merge_tree_min_rows_for_concurrent_read, (20 * 8192), "If at least as many lines are read from one file, the reading can be parallelized.", 0) \
    M(UInt64, merge_tree_min_bytes_for_concurrent_read, (24 * 10 * 1024 * 1024), "If at least as many bytes are read from one file, the reading can be parallelized.", 0) \
    M(UInt64, merge_tree_min_rows_for_seek, 0, "You can skip reading more than that number of rows at the price of one seek per file.", 0) \
    M(UInt64, merge_tree_min_bytes_for_seek, 0, "You can skip reading more than that number of bytes at the price of one seek per file.", 0) \