★ ★ ★ HOW TO DOWNGRADE ORIGIN ★ ★ ★

I don't know why this knowledge isn't more widely known already but I found a way to downgrade to the old Origin, keep it from updating, and go online to play ME3MP.  Not that I really expected to find anything I didn't already know, I stumbled onto this when I was searching for tips on how to handle the Retaliation glitch. (Side note, I actually did fix mine, I'll add that info at the bottom.) EDIT: I'm on Windows 7x64 Enterprise. These instructions should work if you're on Windows 7, but if you're on 8/8.1/10, try the alternate directions from Lvca below.

Here is the thread I found on EA Answers.  To quote:

• Download our old Origin client via www.dm.origin.com/download/legacy
• Run the installer in Vista or XP SP2 compatibility mode (right-click installer -> Properties -> Compatibility)
• Note that Store and Social functions are not available on this Origin version. Any purchases can still be made via the webstore on another device.

I ran mine with Vista compatibility. After confirming I wanted to downgrade, it installed version 9-point-something over the newer version, and I was able to log in with the old interface. Things that didn't work:

• in-game
• achievements
• friends list
• chat
• store? (forgot to test this)

It ran as well as it always did before the forced upgrade to version 10. It started quickly, logged in quickly, showed my games quickly. It only used one low-CPU-usage instance and didn't spawn any of those QtWebEngine processes the newer version does. I played a match online and all the weird lag was gone.

Even if I just wanted to stop there, this would still be pretty amazing, but I wanted to still have access to my friends list somehow, so I decided to try an experiment. I wanted to see if I could have both the old and new version installed side-by-side. Here's what I did:

• With the older version still installed, I renamed the folder Origin was installed in from Origin\ to Origin2\
• I re-ran the Origin installer, this time without compatibility mode enabled
• I verified the newer version loaded fine and that all the functionality was enabled (in-game, friends list, etc.)
• I exited out, went to the Origin2\ folder, and loaded the old Origin

Not only did it work, but I had my friends list, achievements, and chat!

My theory is that there are some shared assets or something somewhere that lets the old version have more functionality when the newer version is installed too. When I click on the "store" tab in the old version, it shows the newer-style store tab, complete with the sidebar menu added to the new Origin.

One extra, extra bonus to using the old version like this: I believe that the join game function works, even if the person you're joining is using the newer version of Origin.

Regarding the Retaliation glitch: I think I picked it up earlier in the day after force-closing ME3, because every subsequent time I tried playing, it would crash either after loading into the main menu, or attempting to quicky jump into the MP menu. A full repair didn't do anything, but a re-sync of my N7HQ profile appears to have fixed it.  After a re-sync, I tried playing again, and while it seemed like it was going to freeze and crash a few times when trying to load into the MP menu, it eventually loaded fine and didn't have any problems or crashes after that.

Anyway hope this helps anyone having trouble with the new Origin, let me know if it works for you (or doesn't).  I forgot to mention it but if it makes any difference, I'm running Windows 7 Enterprise 64-bit.

Edit: formatting

Edit: specified possible differences between Origin on Windows 7 and Origin on newer versions of Windows