Solr replication configuration reports the error 'Invalid URL syntax in "shards" parameter'

Question

After upgrading from Solr 8.1.1 to 8.8.2 I'm seeing an error on the "follower" instance:

Unable to create core [sitecore_web_index]

Invalid URL syntax in 'leaderUrl' with value 'https://searchx.tsta.sxp.local/solr/sitecore_web_index'

Invalid URL syntax in "shards" parameter: null

This is configured with Leader/Follower replication settings found in the solrconfig.xml.

<requestHandler name="/replication" class="solr.ReplicationHandler">
  <lst name="follower">
    <str name="leaderUrl">https://searchx.tsta.sxp.local/solr/${solr.core.name}</str>
    <str name="pollInterval">00:00:20</str>
  </lst>
</requestHandler>

I suspect this has to do with a security issue reported and addressed with 8.8.2: CVE-2021-27905

I found an issue reported on Apache's Jira portal with no response: SOLR-15481

Any steps known to address overcome this issue?

Answer 1

Without any other documentation available, I was able to get the error to go away with the following entry to the solr.in.cmd.

set SOLR_OPTS=%SOLR_OPTS% -Dsolr.disable.shardsWhitelist=true

Answer 2

By disabling the whitelist check entirely. -Dsolr.disable.shardsWhitelist=true update this configuration on solr.in.sh file.

Like:

SOLR_OPTS="$SOLR_OPTS -Dsolr.disable.shardsWhitelist=true"