The commercial version of Oracle's Java JDK 8 - 10 now requires payment for commercial usage(as opposed to general computing usage). Ektron Solr customer's using JDK 8(the only supported Oracle JDK) will either need to pay for Oracle's commercial version or use one of the options below. As of 9.2 SP2 Solr supports OpenJDK versions 8 to 10.
While the Oracle Java JDKs 8 - 10 requires payment, OpenJDK is both free and open source. There are a few parties maintaining OpenJDK, among them is Redhat which has continued to update the 8 and 11+ versions. OpenJDK 10 is the highest supported version for Ektron's Solr(as of 2/20/2020), though Redhat does not appear to update OpenJDK 10. In lieu of OpenJDK 10, Redhat's OpenJDK 8 can be used with Solr for Ektron 9.1 SP3, 9.2SP2, 9.3SP2 and 9.4.
To install the new version uninstall Java through the control panel's programs and features, install the new Java JDK, change the system environment variable(step 3 in critical steps KB), and clear the crawl database.
Redhat OpenJDK Downloads
https://developers.redhat.com/products/openjdk/download ((download the 64 bit MSI to get the installer)