Solr 6.6.0 - Error: can not use FieldCache on multivalued field: categoryLevels

[Vincenzo D'Amore]

Hi,

while trying to run a group query on a multivalue field I received this
error:

can not use FieldCache on multivalued field:

<?xml version="1.0" encoding="UTF-8"?>
<response>

<lst name="responseHeader">
  <bool name="zkConnected">true</bool>
  <int name="status">400</int>
  <int name="QTime">4</int>
</lst>
<lst name="error">
  <lst name="metadata">
    <str name="error-class">org.apache.solr.common.SolrException</str>
    <str name="root-error-class">org.apache.solr.common.SolrException</str>
  </lst>
  <str name="msg">can not use FieldCache on multivalued field:
categoryLevels</str>
  <int name="code">400</int>
</lst>
</response>

I don't understand why this is happening.

Do you know any way to work around this problem?

Thanks in advance,
Vincenzo

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