how to solve - git response 'not something we can merge'

I'm in an environment where the default branch is staging and I'm attempting to run a git merge.  However, in actioning this command, I'm been greeted with the following response 'not something we can merge'

❯ git merge origin/{branch}
merge: origin/{branch} - not something we can merge

To resolve this, first I attempted to do a git checkout to the branch

But this was swiftly meet with "did not match any file(s) known to git"

git checkout {branch}
error: pathspec '{branch}' did not match any file(s) known to git

Git hasn't 'seen' the new branch.  This is where git fetch comes into play.

❯ git fetch origin {branch}
remote: Counting objects: 9, done.
Unpacking objects: 100% (9/9), 721 bytes | 103.00 KiB/s, done.
From https://git-codecommit.ap-southeast.amazonaws.com/v1/repos/{name}
 * branch                {branch} -> FETCH_HEAD
 * [new branch]          {branch} -> origin/{branch}

With the branch recognised

❯ git checkout {branch}
branch '{branch}' set up to track 'origin/{branch}'.
Switched to a new branch '{branch}'

Switch back to your original branch that you wanted to merge.  In my situation I was staging

❯ git checkout staging
Switched to branch 'staging'
Your branch is up to date with 'origin/staging'.

Now I can merge and with success.  Try again. to run git merge

❯ git merge origin/{branch}
Auto-merging web/themes/custom/{project}/... {file path to change(s)}
Merge made by the 'ort' strategy.
 web/themes/custom/{project}/{file-path-to-change} | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)