Option 1: Remove the special characters:
- Access your post type’s categories. For example, →
- Edit any categories with special characters in the name.
Option 2: Install a translation plugin:
If removing the characters is not possible in your language due to missing replacements, or you prefer to use a safer language replacement tool, you can install a translation plugin to load supporting language files for installs in a different language.
If you have WordPress installed in English, but your content is in another language, this is required for proper translation of permalinks and other entities outside of your content.
How to Translate an Obox Theme