EUpgrade on Codeshare
 

I'm curious--- How does eUpgrade work on codeshare flights?

There are numerous threads on this topic...assuming you meant a UA/LH flight number on AC metal plane:

1) Request an upgrade when you check in at the airport.

2) Upgrade is granted at the gate if available.

No advance upgrading is possible.

I believe upgrade can be granted immediately upon request at check-in when upgrade space is not waitlisted. If there is a waitlist, then DaveTO is correct, it will be issued at the gate if your upgrade clears as per the regular order.

When we upgraded UA codeshares on AC metal YVR-EWR recently, there was R space showing on Expertflyer when we requested our upgrades at checkin, but they didn't clear until boarding time (and only then when I prompted).

I got the sense that our requests didn't really integrate into the automated system in the usual way.

All upgrades requested at check in are processed at the gate. (Unless the flight is very wide open in J then there could be some exceptions)