It seems the rollback does not make all the changes necessary for 2.1.27 to read the data. For example:
"skins": [
{
"name": "default",
"attachments": {
Needs to be for 2.1 (delete one { and matching }, also change the matching ] to }):
"skins": {
"default": {
Default values for timelines like time:0, x:0, y:0, or angle:0 are missing. 2.1 requires these.
Some meshes had the wrong number of vertices. Unfortunately I don't see how this can be fixed, except to delete those meshes.
I recovered as much as I could, but it was very time consuming:
I'm sorry there is no good way to convert many files to 2.1. It is an extremely old version, more than 9 years old!
