Background of the issue:
I use WPML on many websites, but only on snoopy.hr I encounter issues. I get a 404 error when switching languages from English to German, then to Croatian, etc. The error appears randomly when switching through languages in the menu.
Symptoms:
404 error on pages and a fatal error caused by WPML string translation.
Questions:
Why do I get a 404 error when switching languages on snoopy.hr?
What causes the fatal error related to WPML string translation?