See PHI2021. An install encountered an error similar to this in their logs:
AH00026: found %2f (encoded '/') in URI (decoded='...'), returning 404
Phabricator legitimately encodes / as %2F in some contexts, and expects Apache to route these requests normally.
...may be relevant here.
The reporting install uses Apache + PHP-FPM, which isn't common. It's possible this is specific to Apache + PHP-FPM.
Likely actions here are:
- Try to reproduce the error.
- See if AllowEncodedSlashes NoDecode fixes it.
- Add a setup self-test for encoding / as %2F, and raise guidance about AllowEncodedSlashes NoDecode.