Affected version: 2.0.757 (Windows)
The bug
Profiles which were created with the old launcher has their names as key in the launcher_profiles.json file instead of a random UUID which every new profile has.
{
"profiles": {
"Snapshots": {
"type": "latest-snapshot",
"lastUsed": "1970-01-01T00:00:00.002Z",
"gameDir": "###"
},
"691a56c5be968605778575592a6a5b85": {
"name": "New profile",
"type": "custom",
"created": "2017-02-04T16:28:52.125Z",
"lastUsed": "1970-01-01T00:00:00.000Z",
"lastVersionId": "latest-release"
}
}