undefined symbol: ngx_stream_upstream_hash_module
change priority symblic link number at /etc/nginx/modules-enabled, especially for all stream modules. use number greater than 50. example: change/rename 50-mod-stream-upsync.conf to 80-mod-stream-upsync.conf # cd /etc/nginx/modules-enabled # mv 50-mod-stream-upsync.conf 80-mod-stream-upsync.conf