JDK 27 Early-Access Release Notes

TLS 1.3 KeyAgreement has been changed to use the Generic key algorithm for Diffie-Hellman shared secrets instead of the TlsPremasterSecret algorithm. This is an implementation detail that should be transparent to the users of the SunJSSE provider, but it may cause handshake failures when using JCE providers that do not support Generic keys.

The finalize() method has been removed from java.util.concurrent.ThreadPoolExecutor.

ThreadPoolExecutor.finalize() was deprecated in JDK 9 as part of deprecating finalization for removal JEP 421. The method was re-specified in JDK 11 to "do nothing" and deprecated for removal in JDK 18.

The removal of this method means that any existing code that extends ThreadPoolExecutor and overrides finalize() to call super.finalize() (or calls finalize() directly) will now call Object.finalize(). This code may no longer compile as Object.finalize() throws Throwable whereas the removed ThreadPoolExecutor.finalize() did not declare any checked exceptions. Developers are strongly encouraged to stop using finalization but if necessary, the source compatibility issue can be worked around using a try-catch.

Support for the java.locale.useOldISOCodes system property in the java.util.Locale class has been removed. Originally introduced in JDK 17, this property allowed applications to revert to legacy ISO 639 language codes ("iw" for Hebrew, "ji" for Yiddish, and "in" for Indonesian). It was deprecated in JDK 25 and, starting with JDK 27, specifying this property has no effect and triggers a warning at runtime. Users who still rely on the old codes are encouraged to transition to the current standard codes: "he" for Hebrew, "yi" for Yiddish, and "id" for Indonesian.