Liferay And Solr: SolrException: can not sort on multivalued field:

If you get this Exception:

org.apache.solr.common.SolrException: can not sort on multivalued field: modified
at org.apache.solr.schema.SchemaField.checkSortability(SchemaField.java:161)
at org.apache.solr.schema.FieldType.getStringSort(FieldType.java:527)
at org.apache.solr.schema.StrField.getSortField(StrField.java:40)
at org.apache.solr.schema.SchemaField.getSortField(SchemaField.java:144)
at org.apache.solr.search.QueryParsing.parseSort(QueryParsing.java:385)
at org.apache.solr.search.QParser.getSort(QParser.java:251)
at org.apache.solr.handler.component.QueryComponent.prepare(QueryComponent.java:82)
at org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:173)
at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:129)
at org.apache.solr.core.SolrCore.execute(SolrCore.java:1368)

then you might be using the liferay solr plugin together with Liferay 6.0.6. Right ?
If so, then continue reading.

Please add the following field to the schema.xml file of the index you are trying to access:
<field name="modified" type="text" indexed="true" stored="true" />

Please also change your SolrIndexSearchImpl and add this to the method "subset", replacing the original code:
 for (String name : names) {
        Field field = new Field(name, 
ArrayUtil.toStringArray(solrDocument.getFieldValues(name).toArray()), false);

There are some posts that helped me on my way to find the solution.
Here they come:


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If you have any questions, feel free to leave a comment.