Error: fts_solr: Lookup failed: 500 Server Error
As per the title, we're seeing multiple entries across multiple email accounts in the dovecot maillog as follows:
Jul 8 12:27:11 dedicated dovecot[1862522]: imap(name@domain.com)<2569479><up3BPWk5cNmaccnK>: Error: fts_solr: Lookup failed: 500 Server Error
Checking the solr logs it seems to be running, but gives logs in 2025_07_08.request.log:
127.0.0.1 - n7TMrlNLAo39T3qW [08/Jul/2025:11:27:11 +0000] "GET /solr/dovecot/select?wt=xml&fl=uid,score&rows=4826&sort=uid+asc&q=%7b!lucene+q.op%3dAND%7d%5c-87de%5cd7f20@email.android.com%3e&fq=%2Bbox:2cde9303e000f923d330+%2Buser:name@domain.com HTTP/1.1" 500 7479
Alma Linux v8.10.0 Standard
cPanel 128.0.15
Please advise.
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I have the same issue.
OS: Rocky Linux v9.6.0
cPanel Version: 128.0.150 -
Although the error in the guide is for the service not starting, have you tried the workaround here?
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Many thanks for your response. Searching the issue before my original post, I saw the page with the solr restart issues and I confirm that cpanel-dovecot-solr is definitely up and restarts OK. Given that Alma Linux v8.10.0 is newer than CentOS 7, I confirm that I did not downgrade tzdata-java. I also checked /etc/sysconfig/cpanel-dovecot-solr the code was already set to use jre-11: SOLR_JAVA_HOME="/usr/lib/jvm/jre-11".
CSF is running on the server and it sends *a lot* of emails, so I missed this initially. But looking at these as part of this issue, for the last 8 days they have included excessive resource usage for the cpanelsolr account with Executable: /usr/lib/jvm/java-11-openjdk-11.0.25.0.9-2.el8.x86_64/bin/java. These appear to have started with a single:
Account: cpanelsolr
Resource: RSS Memory Size
Exceeded: 406 > 256 (MB)
Executable: /usr/lib/jvm/java-11-openjdk-11.0.25.0.9-2.el8.x86_64/bin/java
and then emails every hour starting with:
Account: cpanelsolr
Resource: Process Time
Exceeded: 3624 > 1800 (seconds)
Executable: /usr/lib/jvm/java-11-openjdk-11.0.25.0.9-2.el8.x86_64/bin/java
until the most recent:
Account: cpanelsolr
Resource: Process Time
Exceeded: 712825 > 1800 (seconds)
Executable: /usr/lib/jvm/java-11-openjdk-11.0.25.0.9-2.el8.x86_64/bin/javaSearching this issue I also found reports of 'out of memory' issues for solr. Earlier today, I therefore increased the SOLR_MEMORY to 750m in /etc/sysconfig/cpanel-dovecot-solr before the most recent restart. I wasn't sure if this would help because it was set to 512m and the CSF report relates to RSS Memory Size which appears to be set to 256Mb.
Having updated the memory to 750m and restarted solr, I confirm that the dovecot maillog is still reporting 'Error: fts_solr: Lookup failed: 500 Server Error' across multiple accounts and the CSF resource limit emails are still arriving every hour.
Please advise.
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Seems that this workaround helped me:
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FredQ - at this point it would be best to create a ticket since this doesn't sound like one of the recent known issues with Solr.
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Many thanks KaieR, the recommended workaround on the cPanel page you found has stopped the errors in the logs. The excessive resource usage emails from CSF lfd continue.
However, since you made the update, have you had any issues with resolv.conf?
I.e.
exim -bt user@domain.com, returning
user@domain.tld cannot be resolved at this time: host lookup did not complete0
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