No valid parser for XML

[amztc34283]

Have you checked that your issue isn't already filed?

• I read through FAQ and searched through the past issues, none of which addressed my issue.
• Yes, I have checked that this issue isn't already filed.

Bug description

Feed parser could be loading empty xml file even the format is matching.

How to reproduce the bug

1. Set external_sources in the config file to medium.com and the corresponding rss_url

external_sources:
  - name: medium.com
    rss_url: https://medium.com/@billy.chau./feed

2. docker compose up

Please notice the error does not occur every time and it is hard to predict when will happen.

Error messages and logs

amztc34283githubio-jekyll-1  | "Fetching external posts from medium.com:"
amztc34283githubio-jekyll-1  | /var/lib/gems/3.0.0/gems/feedjira-3.2.3/lib/feedjira.rb:59:in `parse': No valid parser for XML. (Feedjira::NoParserAvailable)
amztc34283githubio-jekyll-1  | 	from /srv/jekyll/_plugins/external-posts.rb:15:in `block in generate'
amztc34283githubio-jekyll-1  | 	from /srv/jekyll/_plugins/external-posts.rb:12:in `each'
amztc34283githubio-jekyll-1  | 	from /srv/jekyll/_plugins/external-posts.rb:12:in `generate'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/site.rb:193:in `block in generate'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/site.rb:191:in `each'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/site.rb:191:in `generate'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/site.rb:79:in `process'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/command.rb:28:in `process_site'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/commands/build.rb:65:in `build'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/commands/build.rb:36:in `process'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/command.rb:91:in `block in process_with_graceful_fail'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/command.rb:91:in `each'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/command.rb:91:in `process_with_graceful_fail'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/lib/jekyll/commands/serve.rb:86:in `block (2 levels) in init_with_program'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `block in execute'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `each'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `execute'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary/program.rb:44:in `go'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary.rb:21:in `program'
amztc34283githubio-jekyll-1  | 	from /var/lib/gems/3.0.0/gems/jekyll-4.3.3/exe/jekyll:15:in `<top (required)>'
amztc34283githubio-jekyll-1  | 	from /usr/local/bin/jekyll:25:in `load'
amztc34283githubio-jekyll-1  | 	from /usr/local/bin/jekyll:25:in `<main>'

What operating system are you using?

Mac

Where are you seeing the problem on?

Running locally with Docker

More info

I suspect this issue is from rendering order but not sure as I have not looked into it.

Update: VPN could also cause the problem.

[george-gca]

Since the error occurs sporadic, it is probably because of your VPN, which may be failing to download the XML atom correctly. Ìf you check feedjira documentation, it states:

Parse XML with first compatible parser

Which means, it checks if the returned (assumed) XML file can be parsed by one of its parsers. This error message is kind of misleading, since it is not that it hasn't a parser, but that the file given to be parsed is not a valid parseable XML file.

[george-gca]

But thinking about it now, it would be useful to add a check if the file was fetched successfully in the external posts plugin. Would you mind sending a PR for this?

[amztc34283]

I am more than happy to create the PR.