The <<88,1>> portion at the end of the binary is the return_context optional, which defaults to 1, as defined in the proto spec. When the 2.* client message is decoded by the server, the missing optional is set to undefined, which causes issues when fetching types:
2020-08-11 07:39:01.028 [error] <0.9599.0> gen_fsm <0.9599.0> in state connected terminated with reason: {error,function_clause,[{riak_kv_pb_crdt,get_context,[<<131,108,0,0,0,2,104,2,109,0,0,0,8,197,82,177,11,162,225,36,190,97,2,104,2,109,0,0,0,12,197,82,177,11,162,225,37,8,0,0,0,1,97,2,106>>,undefined],[ {file,"/home/martincox/code/riak31/_build/default/lib/riak_kv/src/riak_kv_pb_crdt.erl"},{line,271}]},{riak_kv_pb_crdt,process_fetch_response,2,[{file,"/home/martincox/code/riak31/_build/default/lib/riak_kv/src/riak_kv_pb_crdt.erl"}
Adding the defaults_for_omitted_optionals to gpb_opts mitigates the issue.
Older riak clients do not seem to encode optional defaults and possibly rely on the server for decoding and inserting the missing defaults.
Here's a dtfetchreq message from clients:
3.0 client <<10,5,109,121,109,97,112,18,1,49,26,4,109,97,112,115,88,1>> 2.1.0.7 client <<10,5,109,121,109,97,112,18,1,49,26,4,109,97,112,115>>
The <<88,1>> portion at the end of the binary is the return_context optional, which defaults to 1, as defined in the proto spec. When the 2.* client message is decoded by the server, the missing optional is set to undefined, which causes issues when fetching types:
2020-08-11 07:39:01.028 [error] <0.9599.0> gen_fsm <0.9599.0> in state connected terminated with reason: {error,function_clause,[{riak_kv_pb_crdt,get_context,[<<131,108,0,0,0,2,104,2,109,0,0,0,8,197,82,177,11,162,225,36,190,97,2,104,2,109,0,0,0,12,197,82,177,11,162,225,37,8,0,0,0,1,97,2,106>>,undefined],[ {file,"/home/martincox/code/riak31/_build/default/lib/riak_kv/src/riak_kv_pb_crdt.erl"},{line,271}]},{riak_kv_pb_crdt,process_fetch_response,2,[{file,"/home/martincox/code/riak31/_build/default/lib/riak_kv/src/riak_kv_pb_crdt.erl"}Adding the defaults_for_omitted_optionals to gpb_opts mitigates the issue.