JDK 27 Early-Access Release Notes

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.

The JDK will stop trusting TLS server certificates issued after March 17, 2026 and anchored by Chunghwa root certificates, in line with similar plans announced by Google and Mozilla.

TLS server certificates issued on or before March 17, 2026 will continue to be trusted until they expire. Certificates issued after that date, and anchored by the Certificate Authority listed in the table below, will be rejected.

The restrictions are enforced in the JDK implementation (the SunJSSE Provider) of the Java Secure Socket Extension (JSSE) API. A TLS session will not be negotiated if the server's certificate chain is anchored by any of the Certificate Authorities in the table below and the certificate has been issued after March 17, 2026.

An application will receive an exception with a message indicating the trust anchor is not trusted, for example:

"TLS Server certificate issued after 2026-03-17 and anchored by a distrusted legacy Chunghwa root CA: OU=ePKI Root Certification Authority, O="Chunghwa Telecom Co., Ltd." C=TW"

The JDK can be configured to trust these certificates again by removing "CHUNGHWA_TLS" from the jdk.security.caDistrustPolicies security property in the java.security configuration file.

The restrictions are imposed on the following Chunghwa Root certificates included in the JDK:

You can also use the keytool utility from the JDK to print out details of the certificate chain, as follows:

keytool -v -list -alias <your_server_alias> -keystore <your_keystore_filename>

If any of the certificates in the chain are issued by one of the root CAs in the table above are listed in the output you will need to update the certificate or contact the organization that manages the server