Open Ondemad stop working suddenly

I had a working ondemand session. But it suddenly stops working.

Now each time when I try to login it gives me the following error. What could be the reason?

Error -- /opt/ood/nginx_stage/lib/nginx_stage/configuration.rb:469:in `read_configuration': undefined method `each' for #<String:0x0000000002c08f58> (NoMethodError)
	from /opt/ood/nginx_stage/lib/nginx_stage/configuration.rb:461:in `set_default_configuration'
	from /opt/ood/nginx_stage/lib/nginx_stage/configuration.rb:385:in `extended'
	from /opt/ood/nginx_stage/lib/nginx_stage.rb:38:in `extend'
	from /opt/ood/nginx_stage/lib/nginx_stage.rb:38:in `<module:NginxStage>'
	from /opt/ood/nginx_stage/lib/nginx_stage.rb:25:in `<top (required)>'
	from /opt/rh/rh-ruby24/root/usr/share/rubygems/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /opt/rh/rh-ruby24/root/usr/share/rubygems/rubygems/core_ext/kernel_require.rb:55:in `require'

That section of code (configuration.rb) processes the Nginx configuration file which is expected to be a YAML document. Your error shows that when the YAML parser processed the file it returned a string and not a mapping; so it looks like your configuration file (/etc/ood/config/nginx_stage.yml) has become invalid. Our example for nginx_stage.yml is available here:

It solved the problem. nginx_stage.yml was corrupted somehow. Thanks @rodgers.355