To replicate:
- Go to https://tools.wmflabs.org/wikiloves/monuments/2017
- Click the number in the column 'uploaders' for any country with multiple words. For example, United States or South Korea
- A url is linked to like https://tools.wmflabs.org/wikiloves/monuments/2017/United_States
The error produced is "Country not found" with the message
This page do not exist in the server.
Be sure the address is correct.
If the problem precists contact the developers or create a task in Phabricator.