When upgrading to the latest DSE 3.2.x, you'll get a conflict when adding new columns/fields as the name of the class implementing the Solr secondary index changed between versions: this caused your problems above.
DSE 3.2.2 will fix this issue, but in the meantime you can follow the given steps:
- Restart the node with Solr disabled.
- Describe your schema via CQLSH and identify the added columns with related Cassandra secondary indexes: you'll notice class names differ from already existent indexes.
- Drop each new index and create again with exactly the same name, but changing the class name to match the old one.
- Restart with Solr enabled and everything should work.