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In case there is a requirement to keep working with Zend Server on a CentOS 8 machine, before we move to Rocky Linux 8,and there is no replacement RHEL 8 host to migrate to, there is an option to change the CentOS 8 repositories to the Vault copies,
which are not further updates anymore, but exists and will allow yum to continue working for 3rd party software like Zend Server, using zend.com repos.
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Once the repos have been changed, you can install / upgrade Zend Server on the machine(s).
Zend Support recommends to use a supported and updated OS for Zend Server, as listed under from the System Requirements.
Current alternatives to CentOS 8 would be Open Logic repos, and RHEL 8.
We plan to add support for Rocky Linux 8 in the near future, and retire CentOS 8 from further releases.
If you have any concern or issue regarding this information, please address those with Zend Global Support.