"Page Not Found" page is not encoded correctly, when attempting to access a non-existent space with German/French/Spanish and many other languages in the User Profile

Issue Summary

This is reproducible on Data Center: yes

Steps to Reproduce

1. Install Confluence Data Center 8.5.6 or 8.5.7
2. Set the Profile Language to Deutsch or many of the other langauges (French, Spanish, Danish, etc) - <yoursite>/users/editmysettings.action
3. Browse to a URL that contains a space that does not exist - <yoursite>/display/non-existentspace

Note: This does not occur in 7.19.x and below.

Expected Results

That the "Page Not Found" page is encoded properly.

Actual Results

Special characters are rendered incorrectly, for example, "Wir können diese Seite nicht finden. Möglicher Grund:"

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available