Async jobs failing

I'm using Rhoconnect 6.2 gem. Everything works fine until I would like to use async source jobs:

settings.yml:

:sources:
    Image:
        :poll_interval: 0
        :priority: 4
        :partition_type: app
        :pass_through: false
        :queue: image

Resque error message:

Redis:CommandError: ERR Syntax error, try CLIENT (LIST | KILL | GETNAME | SETNAME | PAUSE | REPLY)

I'm using Redis 4.0.14.

My Gemfile.lock:

GIT
remote: github.com/tauplatform/async-rack.git
revision: 4f411e7b416894a52426eb3b26c2415e5ead927e
specs:
async-rack (0.5.2)
rack (~> 2.0)

GEM
remote: rubygems.org/
specs:
aws-eventstream (1.0.3)
aws-sdk (2.11.280)
aws-sdk-resources (= 2.11.280)
aws-sdk-core (2.11.280)
aws-sigv4 (~> 1.0)
jmespath (~> 1.0)
aws-sdk-resources (2.11.280)
aws-sdk-core (= 2.11.280)
aws-sigv4 (1.1.0)
aws-eventstream (~> 1.0, >= 1.0.2)
connection_pool (2.2.2)
daemons (1.3.1)
diff-lcs (1.3)
domain_name (0.5.20180417)
unf (>= 0.0.5, < 1.0.0)
dotenv (2.7.2)
eventmachine (1.0.9.1)
faraday (0.15.4)
multipart-post (>= 1.2, < 3)
http-cookie (1.0.3)
domain_name (~> 0.5)
jmespath (1.4.0)
json (1.8.6)
jwt (2.1.0)
mime-types (3.2.2)
mime-types-data (~> 3.2015)
mime-types-data (3.2019.0331)
mono_logger (1.1.0)
multi_json (1.13.1)
multi_xml (0.6.0)
multipart-post (2.1.1)
mustermann (1.0.3)
netrc (0.11.0)
oauth2 (1.4.1)
faraday (>= 0.8, < 0.16.0)
jwt (>= 1.0, < 3.0)
multi_json (~> 1.3)
multi_xml (~> 0.5)
rack (>= 1.2, < 3)
rack (2.0.7)
rack-fiber_pool (0.9.3)
rack-protection (2.0.5)
rack
rack-test (0.8.3)
rack (>= 1.0, < 3)
rake (12.3.2)
redis (4.1.1)
redis-namespace (1.6.0)
redis (>= 3.0.4)
resque (2.0.0)
mono_logger (~> 1.0)
multi_json (~> 1.0)
redis-namespace (~> 1.6)
sinatra (>= 0.9.2)
vegas (~> 0.1.2)
rest-client (2.0.2)
http-cookie (>= 1.0.2, < 2.0)
mime-types (>= 1.16, < 4.0)
netrc (~> 0.8)
rhoconnect (6.2.0)
bundler (~> 1.17.3)
connection_pool (~> 2.2.2)
json (>= 1.8, < 2.0)
rack (~> 2.0.6)
rake (~> 12.3.2)
redis (~> 4.1.0)
resque (>= 2.0.0)
rest-client (~> 2.0.2)
rubyzip (~> 1.2.2)
sinatra (~> 2.0.5)
thor (~> 0.20.3)
rhomobile-debug (1.0.7)
rspec (2.99.0)
rspec-core (~> 2.99.0)
rspec-expectations (~> 2.99.0)
rspec-mocks (~> 2.99.0)
rspec-core (2.99.2)
rspec-expectations (2.99.2)
diff-lcs (>= 1.1.3, < 2.0)
rspec-mocks (2.99.4)
rubyzip (1.2.2)
sinatra (2.0.5)
mustermann (~> 1.0)
rack (~> 2.0)
rack-protection (= 2.0.5)
tilt (~> 2.0)
thin (1.7.2)
daemons (~> 1.0, >= 1.0.9)
eventmachine (~> 1.0, >= 1.0.4)
rack (>= 1, < 3)
thor (0.20.3)
tilt (2.0.9)
unf (0.1.4)
unf_ext
unf_ext (0.0.7.6)
vegas (0.1.11)
rack (>= 1.0.0)

PLATFORMS
ruby

DEPENDENCIES
async-rack!
aws-sdk (~> 2.11, >= 2.11.280)
dbd-jdbc (>= 0.1.4)
dbi (>= 0.4.5)
dotenv (~> 2.7, >= 2.7.2)
eventmachine (~> 1.0.5)
jdbc-sqlite3 (>= 3.7.2)
oauth2 (~> 1.4, >= 1.4.1)
puma (~> 1.6.0)
rack-fiber_pool
rack-test (~> 0.6)
rhoconnect (~> 6.2)
rhomobile-debug (>= 1.0.2)
rspec (~> 2.14)
thin
warbler
win32-api (= 1.4.5)
win32-process (= 0.6.6)

RUBY VERSION
ruby 2.6.3p62

BUNDLED WITH
1.17.3