When you try to connect your Code 50 to the Marshall Gateway app, make sure you have performed "Forget This Device" on all the other Bluetooth enabled devices near by that could be detecting your Code 50.

Thank you, but that didn't work. Marshall is an Amp Company not a software company. I realy didn't expect it to work. when you don't keep up with the updates this happens. I just gave up with the crappy app. It just takes longer to get setup. wish the app worked.

I bought a used Code 50 in February 2022. I'm using a phone about five years old to run the app on.

When I first downloaded the app and attempted to connect to it, it would only connect to allow me to play music through the app into the amp. I tried connecting again several times and then actually went ahead and played music from Spotify through the amp. Suddenly, the app "connected" properly and allows me to control the amp the way that it was designed and I have not had a problem since.

It seemed to be more of a bluetooth problem than an actual app to amp problem.

I don't know if any of this will help your situation, but hopefully things work out for you.

I had the same issue. Took it into PMT and my Amp connected to the guy in the shops phone. I then bought a Samsung tablet ansd it works fine but for some reason wouldnt connect to the app on my Samsung phone

Pursued using the Marshal Gateway (Android) app, on Code 50, which by design only connects after a Bluetooth Audio connection is active on same device you intend to use for running Marshall Gateway app.

But Marshall Gateway could never connect

Updated the Code 50 to latest firmware, had to use a Windows 10 laptop and Chrome browser MIDI USB Connect to use the Code50 Firmware update tools , it took several tries, as it updated firmware for boot loader, DSP, Bluetooth and MCU

After installing latest firmware , Marshall Gateway Android app still refused to locate the Marshall Code 50 and make connection.

Finally on a "MyMarshall message board I found this important step

For anyone who is having the same issue, what worked for me is the following. Note that I'm using a Galaxy S8 and the process could be different depending on what phone you are using.
"Reset network settings
1. From Home screen, touch and swipe up or down to display all apps.
2. Navigate: Settings > General management.
3. Tap Reset network settings.
4. Tap Reset settings.
5. If applicable, enter the PIN, password, fingerprint, or pattern then tap Reset again to confirm.

NOTE: This will reset ALL network settings including saved Wi-Fi passwords.

I hope this solves it for all of you having simillar issues. Thanks Marshall for the support and thank you for a killer AMP"

So I Reset all my Android Network settings, rebooted my Samsung Galaxy S10+ phone (Android 12)  , and made the Bluetooth Audio Pair connection (mandatory) , then launched Marshall Gateway app (V1.5.5) (Code50 patch Editor /Librarian) , and finally the app could locate the Code 50 and make a connection (1st time thats worked in over 6 years!