Gitlab merge request gives 500 Internal Server Error for a specific branch

Gitlab merge request gives 500 Internal Server Error for a specific branch
we are currently on gitlab 13.2.4 ee.

Below are the logs.
grpc-1.24.0-x86_64 (linux) src/ruby/lib/grpc/generic/active_call.rb:31:in `check_status’

grpc-1.24.0-x86_64 (linux) src/ruby/lib/grpc/generic/active_call.rb:181:in `attach_status_results_and_complete_call’

grpc-1.24.0-x86_64 (linux) src/ruby/lib/grpc/generic/active_call.rb:170:in `receive_and_check_status’

grpc-1.24.0-x86_64 (linux) src/ruby/lib/grpc/generic/active_call.rb:338:in `each_remote_read_then_finish’

puma: cluster worker 6: 22232 [gitlab-puma-worker]:1:in `each’

Completed 500 Internal Server Error in 56982ms (ActiveRecord: 36.9ms | Elasticsearch: 0.0ms | Allocations: 1881515)

GRPC::DeadlineExceeded (4:Deadline Exceeded):

Anyone has faced similar issue or if any suggestions on how to debug ??