Two environments. Same Connections version, same CR level, byte-identical application JARs, byte-identical mod_ibm_upload.so. On one of them, Upload through IBM HTTP Server (IHS) works perfectly. On the other, every upload above the configured threshold returns HTTP 500.
It took two days to find out why, and the answer had nothing to do with Connections, WebSphere or IHS. It was in the NFS mount options, and not the ones you would expect.
This is a companion discussion topic for the original entry at https://blog.martdj.nl/2026/09/15/when-upload-through-ihs-fails-a-30-second-nfs-mystery/