Rails app - Capistrano deployment failing - ruby-on-rails

Question

I have an existing Rails application that is set up to use Capistrano for deployments. I'm adding a Staging environment to it, but running bundle exec cap staging deploy returns an error:
cap aborted!
SSHKit::Runner::ExecuteError: Exception while executing as deploy#[IP Redacted]: cat /var/www/staging-app-name/current/REVISION exit status: 1
cat /var/www/staging-app-name/current/REVISION stdout: Nothing written
cat /var/www/staging-app-name/current/REVISION stderr: cat: /var/www/staging-app-name/current/REVISION: No such file or directory
Versions:
Rails - 4.2.11
Ruby - 2.3.1
Capistrano - 3.15.0
Deploy.rb:
set :stages, %w(production staging)
set :application, "application-name"
set :repo_url, "[Redacted]"
set :conditionally_migrate, !ENV['FIRST_RUN']
set :migration_role, :app
set :default_stage, "production"
set :linked_files, fetch(:linked_files, []).push('config/database.yml', 'config/secrets.yml')
set :linked_dirs, fetch(:linked_dirs, []).push(
'log',
'tmp/pids',
'tmp/cache',
'tmp/sockets',
'vendor/bundle',
'public/system',
'public/uploads',
'public/assets'
)
set :default_env, { path: "/opt/ruby_build/builds/2.3.1/bin:$PATH" }
deploy/staging.rb:
server '[IP redacted]', user: 'deploy', roles: %w{app db web}
set :branch, 'develop'
set :deploy_to, '/var/www/staging-app-name'
set :stage, 'staging'
set :rails_env, 'staging'
deploy/production.rb
server '[IP redacted]', user: 'deploy', roles: %w{app db web}
set :branch, 'master'
set :deploy_to, '/var/www/production-app-name'
set :stage, 'production'
set :rails_env, 'production'
Capfile
# Load DSL and set up stages
require "capistrano/setup"
# Include default deployment tasks
require "capistrano/deploy"
require "capistrano/scm/git"
install_plugin Capistrano::SCM::Git
require "capistrano/bundler"
require "capistrano/rails/migrations"
require "capistrano/conditional"
# Load custom tasks from `lib/capistrano/tasks` if you have any defined
Dir.glob("lib/capistrano/tasks/*.rake").each { |r| import r }
This would be the first Staging deployment, so the staging-app-name directory is empty.
It's worth noting that Production deployments are working.
I've confirmed the directory/file permissions on the server are fine.
Any help would be appreciated!