Currently, there are a number of tickets open to address problems where Confluence allows characters in page names that then cause problems in WebDAV, such as but not limited to these characters:

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I suggest an admin-level option that prevents contributors from saving page names that contain problem characters. One possible implementation would be a checkbox in the Confluence admin > WebDAV settings where admins could choose to disallow known WebDAV-problematic characters in page titles. If this option were enabled, and then content contributors were to try to save a page name with these banned characters, Confluence would show an error message similar to the error it shows when one saves a page with a blank page name, possibly with the suggestion that contributor use accepted special characters instead such as "-" and "_" or simply a blank space " ".