Re: Upgrading Solr 6.3.0 to 7.5.0 without having to re-index

[Shawn Heisey]

On 4/17/2019 3:52 AM, Ritesh Kumar wrote:
Field type in old configuration - string (solr.StrField)   indexed and
stored set to true.
Field type in new configuration - solr.SortableTextField (docValues enabled)

On your schema, you have changed the field class -- from StrField to 
SortableTextField.  Which, by the way, isn't going to work without a 
reindex even if there are no docValues problems.  You also changed the 
docValues flag, which can sometimes change the docValues type at the 
Lucene level.

If a field has its Lucene docValues type changed, indexing is going to 
fail.  The index will have to be completely deleted, restarted, and 
rebuilt from scratch.  If the index directory is not deleted completely, 
then the error you saw will continue even through a reindex.

Thanks,
Shawn