The language string is missing for "member_photo_url".

It happens on my default skin, so it's not related to my third-party ones.

Where are you seeing this being shown? I've done a search through the files, and I'm not seeing this string being used anywhere. The string itself was removed in 4.5.0 (specifically, the first beta).

43 minutes ago, Ryan Ashbrook said:

Where are you seeing this being shown? I've done a search through the files, and I'm not seeing this string being used anywhere. The string itself was removed in 4.5.0 (specifically, the first beta).

When choosing a location where to change my display picture.

This is likely due to the Avatars Gallery application. I can confirm we removed this option long ago, and that application appears to be overriding the form. It needs to be updated for 4.6.