A script to update UIDs for Roam Research graph exports.
cat my-roam-export.json | python fixroam.py > updated-export.json
Export your Roam graph, delete all your pages, and try to re-import that same graph. Roam will complain that "blocks already exist" and will fail to import, but won't give you more helpful info than that.
Updating UIDs appears to solve 99% of these issues.
It turns out that 4 / 474 of my notes still were inexplicably unable to import back into my graph, even after updating UIDs.
To find these, I basically outputted my script results and continuously whittled the result set down using jq like so:
$ cat my-roam-export.json | python fixroam.py | jq 'length'
474
$ cat my-roam-export.json | python fixroam.py | jq '.[0:256]' > subset.json
... attempt import, get error ...
$ cat my-roam-export.json | python fixroam.py | jq '.[0:128]' > subset.json
... attempt import, get error ...
$ cat my-roam-export.json | python fixroam.py | jq '.[0:64]' > subset.json
... attempt import, no error!
$ cat my-roam-export.json | python fixroam.py | jq '.[64:96]' > subset.json
... attempt import, get error ...
... and so on and so forth ...
After identifying the problematic notes, I added their titles to the BLACKLIST list in the script to remove them from the output, and kept on truckin' until I got the whole functioning batch to import.