Salut @stephdl,
PH32435: ENCODED CHARCTERS (%2F ETC) IN URI.
WebSphere Application Server for IBM i.
Client unable to access WebSphere through HTTP Server/plugin when there is encoded charcters (%2f etc) in URI.
This symptom occurs when client access WebSphere through HTTP Server/plugin.
This symptom does not occur when client access WebSphere directly (not through HTTP Server/plugin).
https://www.ibm.com/support/pages/apar/PM31189.
Problem conclusion
A new value for AllowEncodedSlashes was added, "NoDecode", which accepts URLs with encoded slashes in the path info but does not decode them.
Michel-André