restoring backup leads to error

I tried to restore a backup and get the following error after the database scripts have been processed:

Restoring repositories ...
 * ESID/OSSE-XML-export ... rake aborted!
GRPC::Unavailable: 14:Connect Failed
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/grpc-1.11.0-x86_64-linux/src/ruby/lib/grpc/generic/active_call.rb:31:in `check_status'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/grpc-1.11.0-x86_64-linux/src/ruby/lib/grpc/generic/active_call.rb:180:in `attach_status_results_and_complete_call'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/grpc-1.11.0-x86_64-linux/src/ruby/lib/grpc/generic/active_call.rb:372:in `request_response'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/grpc-1.11.0-x86_64-linux/src/ruby/lib/grpc/generic/client_stub.rb:178:in `block in request_response'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/grpc-1.11.0-x86_64-linux/src/ruby/lib/grpc/generic/interceptors.rb:170:in `intercept!'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/grpc-1.11.0-x86_64-linux/src/ruby/lib/grpc/generic/client_stub.rb:177:in `request_response'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/grpc-1.11.0-x86_64-linux/src/ruby/lib/grpc/generic/service.rb:170:in `block (3 levels) in rpc_stub_class'
/home/git/gitlab/lib/gitlab/gitaly_client.rb:139:in `call'
/home/git/gitlab/lib/gitlab/gitaly_client/namespace_service.rb:35:in `gitaly_client_call'
/home/git/gitlab/lib/gitlab/gitaly_client/namespace_service.rb:17:in `add'
/home/git/gitlab/lib/gitlab/shell.rb:297:in `add_namespace'
/home/git/gitlab/app/models/storage/legacy_project.rb:27:in `ensure_storage_path_exists'
/home/git/gitlab/app/models/project.rb:54:in `ensure_storage_path_exists'
/home/git/gitlab/lib/backup/repository.rb:138:in `block in restore'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/activerecord-4.2.10/lib/active_record/relation/batches.rb:51:in `block (2 levels) in find_each'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/activerecord-4.2.10/lib/active_record/relation/batches.rb:51:in `each'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/activerecord-4.2.10/lib/active_record/relation/batches.rb:51:in `block in find_each'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/activerecord-4.2.10/lib/active_record/relation/batches.rb:124:in `find_in_batches'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/activerecord-4.2.10/lib/active_record/relation/batches.rb:50:in `find_each'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/activerecord-4.2.10/lib/active_record/querying.rb:9:in `find_each'
/home/git/gitlab/lib/backup/repository.rb:135:in `restore'
/home/git/gitlab/lib/tasks/gitlab/backup.rake:87:in `block (4 levels) in <top (required)>'
/home/git/gitlab/lib/tasks/gitlab/backup.rake:60:in `block (3 levels) in <top (required)>'
/home/git/gitlab/vendor/bundle/ruby/2.3.0/gems/rake-12.3.1/exe/rake:27:in `<top (required)>'
Tasks: TOP => gitlab:backup:repo:restore
(See full trace by running task with --trace)

Start with lib/tasks/gitlab/backup.rake and lib/backup/repository.rb at the gitlab:backup:repo:restore entry point, then trace the Gitaly call through lib/gitlab/gitaly_client/namespace_service.rb. Use the supplied restore output to investigate the GRPC::Unavailable failure; done means the repository restore completes without this error.