Heroku Redis max memory error -

my production environment has started throwing error:

error fetching message: err error running script (call f_0ab965f5b2899a2dec38dec41fff8c97f7a33ee9): @user_script:56: @user_script: 56: -oom command not allowed when used memory > 'maxmemory'. 

i using heroku redis addon worker dyno running sidekiq.

both redis , worker dyno have plenty of memory right , logs don't show them running out.

what causing error thrown , how can fix it?

run "config maxmemory" on redis server. maybe config limiting amount of memory redis using.