Merging Dev Problem

Hi,
I met a problem when I want to merge branches.
To explain, I have 3 branches in my app and I want to synchronize the three.
The problem i am having is when I want to merge the dev I always have this message from bubble (see the image).
I tried to push all the changes to Live and after that sync the dev with the Live.
Everything was fine for the first step but when I had to sync the Dev with the Live, I had the same message.

If someone can help me…
Capture d’écran 2022-07-13 110953

I don’t think you can merge Live into any other branch. You should merge all branches/versions to development and when you know development is bug free, then push that version to live.