If you get one of this errors:

Error: Could not retrieve catalog from remote server: Error 400 on SERVER: (<unknown>): found character that cannot start any token while scanning for the next token at line 1297 column 3
Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run

Error: Could not retrieve catalog from remote server: Error 400 on SERVER: undefined method `empty?' for nil:NilClass at /etc/puppet/environments/production/manifests/nodes.pp:1 on node example.makandra.de
Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run

Do you need DevOps-experts?

Your development team has a full backlog? No time for infrastructure architecture? Our DevOps team is ready to support you!

• We build reliable cloud solutions with Infrastructure as code
• We are experts in security, Linux and databases
• We support your dev team to perform

Read more Show archive.org snapshot

it's probably an error in your hiera yaml files.

In my case it was a facter variable I've used without quotes after a puppetmaster update (it was working for months before that).

Bad:

foo: %{::fqdn}

Good:

foo: "%{::fqdn}"

I've debugged the error like this:

• deleted all yaml files one by one until the error didn't happend
• comment out all lines in this yaml and removed the comments step by step until I've found the bad line