Error after update (uninitialized constant)

Hello,

I just did an update of gitlab 12.3 => 12.10 and my BackgroundMigrations is stuck at 24 remaining tasks. I find in the sidekiq’s log, there is error uninitialized constant Gitlab::BackgroundMigration::DeserializeMergeRequestDiffsAndCommits

{"severity":"WARN","time":"2020-09-29T09:41:33.490Z","error_class":"NameError","error_message":"uninitialized constant Gitlab::BackgroundMigration::DeserializeMergeRequestDiffsAndCommits","context":"Job raised exception","jobstr":"{\"class\":\"BackgroundMigrationWorker\",\"args\":[\"DeserializeMergeRequestDiffsAndCommits\",[2528,5085]],\"retry\":3,\"queue\":\"background_migration\",\"jid\":\"b573ebda23d7a5db8437b7ca\",\"created_at\":1601372412.5370986,\"meta.caller_id\":\"DeserializeMergeRequestDiffsAndCommits\",\"correlation_id\":\"ddd72bbab8d327b076c7ad8b0286a724\",\"enqueued_at\":1601372493.433596}","class":"BackgroundMigrationWorker","args":["DeserializeMergeRequestDiffsAndCommits","[2528, 5085]"],"retry":3,"queue":"background_migration","jid":"b573ebda23d7a5db8437b7ca","created_at":"2020-09-29T09:40:12.537Z","meta.caller_id":"DeserializeMergeRequestDiffsAndCommits","correlation_id":"ddd72bbab8d327b076c7ad8b0286a724","enqueued_at":"2020-09-29T09:41:33.433Z","error_backtrace":["lib/gitlab/background_migration.rb:103:in `const_get'","lib/gitlab/background_migration.rb:103:in `migration_class_for'","lib/gitlab/background_migration.rb:58:in `perform'","app/workers/background_migration_worker.rb:30:in `block in perform'","app/workers/concerns/worker_context.rb:63:in `block in with_context'","lib/gitlab/application_context.rb:52:in `block in use'","lib/gitlab/application_context.rb:52:in `use'","app/workers/concerns/worker_context.rb:63:in `with_context'","app/workers/background_migration_worker.rb:26:in `perform'","lib/gitlab/with_request_store.rb:7:in `with_request_store'","lib/gitlab/sidekiq_daemon/monitor.rb:49:in `within_job'"]}

Do you know how to fix these errors?
Thank you for your help.