Python – RabbitMQ management API call failed: HTTP 500: Internal Server Error

I am using Celery Flower with RabbitMQ as message broker. However I am :getting nasty error

ERROR – RabbitMQ management API call failed: HTTP 500: Internal Server Error

every time I try to access RabbitMQ queues on RabbitMQ management interface (http://localhost:15672/#/queues) or Celery Broker (http://localhost:5555/broker).

Here is a detailed log info:

=ERROR REPORT==== 15-Jan-2017::23:12:19 === webmachine error: path="/api/queues/%2F" {error,{error,function_clause,
[{mochijson2,json_encode_string_unicode,
[{error,[],<<166,65,92,180,0,0,0,0,0>>}, {encoder,null,false}, """],
[{file,"src/mochijson2.erl"},{line,274}]},
{mochijson2,'-json_encode_proplist/2-fun-0-',3,
[{file,"src/mochijson2.erl"},{line,198}]},
{lists,foldl,3,[{file,"lists.erl"},{line,1248}]},
{mochijson2,json_encode_proplist,2,
[{file,"src/mochijson2.erl"},{line,202}]},
{mochijson2,'-json_encode_proplist/2-fun-0-',3,
[{file,"src/mochijson2.erl"},{line,199}]},
{lists,foldl,3,[{file,"lists.erl"},{line,1248}]},
{mochijson2,json_encode_proplist,2,
[{file,"src/mochijson2.erl"},{line,202}]},
{mochijson2,'-json_encode_array/2-fun-0-',3,
[{file,"src/mochijson2.erl"},{line,189}]}]}}

RabbitMQ web management gives me:

Got response code 500 with body {"error":"Internal Server
Error","reason":"{error,{error,function_clause,\n
[{mochijson2,json_encode_string_unicode,\n
[{error,[],<<166,65,92,180,0,0,0,0,0>>},\n {encoder,null,false},\n
"\""],\n [{file,"src/mochijson2.erl"},{line,274}]},\n
{mochijson2,'-json_encode_proplist/2-fun-0-',3,\n
[{file,"src/mochijson2.erl"},{line,198}]},\n
{lists,foldl,3,[{file,"lists.erl"},{line,1248}]},\n
{mochijson2,json_encode_proplist,2,\n
[{file,"src/mochijson2.erl"},{line,202}]},\n
{mochijson2,'-json_encode_proplist/2-fun-0-',3,\n
[{file,"src/mochijson2.erl"},{line,199}]},\n
{lists,foldl,3,[{file,"lists.erl"},{line,1248}]},\n
{mochijson2,json_encode_proplist,2,\n
[{file,"src/mochijson2.erl"},{line,202}]},\n
{mochijson2,'-json_encode_array/2-fun-0-',3,\n
[{file,"src/mochijson2.erl"},{line,189}]}]}}\n"}

I am using:

• Ubuntu 14.04
• Python 2.7.6
• Flower 0.9.1
• Celery 4.0.2
• RabbitMQ 3.6.6
• Erlang/OTP 19

RabbitMQ management plugin is enabled (rabbitmq-plugins enable rabbitmq_management).

Here is the output for rabbitmqctl status:

[{pid,28609}, {running_applications,
[{rabbitmq_management,"RabbitMQ Management Console","3.6.6"},
{amqp_client,"RabbitMQ AMQP Client","3.6.6"},
{rabbitmq_management_agent,"RabbitMQ Management Agent","3.6.6"},
{rabbitmq_web_dispatch,"RabbitMQ Web Dispatcher","3.6.6"},
{rabbit,"RabbitMQ","3.6.6"},
{os_mon,"CPO CXC 138 46","2.4.1"},
{webmachine,"webmachine","1.10.3"},
{mochiweb,"MochiMedia Web Server","2.13.1"},
{ssl,"Erlang/OTP SSL application","8.1"},
{public_key,"Public key infrastructure","1.3"},
{crypto,"CRYPTO","3.7.2"},
{rabbit_common,[],"3.6.6"},
{xmerl,"XML parser","1.3.12"},
{asn1,"The Erlang ASN1 compiler version 4.0.4","4.0.4"},
{syntax_tools,"Syntax tools","2.1.1"},
{mnesia,"MNESIA CXC 138 12","4.14.2"},
{compiler,"ERTS CXC 138 10","7.0.3"},
{ranch,"Socket acceptor pool for TCP protocols.","1.2.1"},
{inets,"INETS CXC 138 49","6.3.4"},
{sasl,"SASL CXC 138 11","3.0.2"},
{stdlib,"ERTS CXC 138 10","3.2"},
{kernel,"ERTS CXC 138 10","5.1.1"}]}, {os,{unix,linux}}, {erlang_version,
"Erlang/OTP 19 [erts-8.2] [source] [64-bit] [smp:4:4] [async-threads:64] [kernel-poll:true]\n"}, {memory,
[{total,112070616},
{connection_readers,471152},
{connection_writers,171664},
{connection_channels,494680},
{connection_other,407232},
{queue_procs,534792},
{queue_slave_procs,0},
{plugins,2121728},
{other_proc,12017232},
{mnesia,93584},
{mgmt_db,5114688},
{msg_index,49304},
{other_ets,1902144},
{binary,52694768},
{code,24783822},
{atom,1033401},
{other_system,10180425}]}, {alarms,[]}, {listeners,[{clustering,25672,"::"},{amqp,5672,"::"}]},
{vm_memory_high_watermark,0.4}, {vm_memory_limit,6691391078},
{disk_free_limit,50000000}, {disk_free,59039645696},
{file_descriptors,
[{total_limit,3996},
{total_used,23},
{sockets_limit,3594},
{sockets_used,20}]}, {processes,[{limit,1048576},{used,454}]}, {run_queue,0}, {uptime,2498}, {kernel,{net_ticktime,60}}]

Here is how I run Celery:

Start 3 celery workers:

celery worker -A celeryapp --config celeryconfig --workdir /proj -l DEBUG --soft-time-limit=3500 --time-limit=3600 --autoscale=2,1 -S /proj/states.db -s /proj/celerybeat-schedule.db -f /proj/logs/celery_worker_1_%n%I.log --pidfile /tmp/celery_w1.pid -n worker1@%d
celery worker -A celeryapp --config celeryconfig --workdir /proj -l DEBUG --soft-time-limit=3500 --time-limit=3600 --autoscale=2,1 -S /proj/states.db -s /proj/celerybeat-schedule.db -f /proj/logs/celery_worker_2_%n%I.log --pidfile /tmp/celery_w2.pid -n worker2@%d
celery worker -A celeryapp --config celeryconfig --workdir /proj -l DEBUG --soft-time-limit=3500 --time-limit=3600 --autoscale=2,1 -S /proj/states.db -s /proj/celerybeat-schedule.db -f /proj/logs/celery_worker_3_%n%I.log --pidfile /tmp/celery_w3.pid -n worker3@%d

Start celery beat:

celery beat -A celeryapp --config celeryconfig --workdir /proj -l DEBUG -s /proj/celerybeat-schedule.db -f /proj/logs/celery_%n%I.log --pidfile /tmp/celery.pid

Start celery flower:

celery flower -A celeryapp --workdir=/proj/ --broker=amqp://guest:guest@localhost:5672// --broker-api=http://guest:guest@localhost:15672/api/ --db=/proj/flower.db --logging=debug --basic-auth=guest:guest

I posted this question in Github issues of RabbitMQ but it was rejected