[Gradle 9+] 'Gradle requires JVM 17 or later to run. Your build is currently configured to use JVM 8.' — daemon JVM taken from JAVA_HOME (CI images/Codespaces default to Java 8/11)

Cause (Documented platform behavior): Starting in Gradle 9.0.0 the daemon requires JVM 17+; clients (wrapper, Tooling API) still run on JVM 8. Without daemon JVM criteria, the daemon uses JAVA_HOME and does not auto-fallback (feature request #39061 open). Fix status: documented_behavior Misleading approaches: - Downgrading project source/target compatibility — it is the daemon runtime JVM that must be 17+, not the compile target Unknowns: - Whether #39061 auto-fallback will ship Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/gradle/gradle/master/platforms/documentation/docs/src/docs/userguide/releases/upgrading/upgrading_version_8.adoc (official_docs, unknown, documented_behavior): Starting in Gradle 9.0.0 the daemon requires JVM 17+; clients stay JVM 8-compatible; configure via Daemon JVM criteria, org.gradle.java.home, Tooling API setJavaHome, or set JAVA_HOME to 17+; code can still target JVM 6+. - https://raw.githubusercontent.com/gradle/gradle/master/platforms/documentation/docs/src/docs/userguide/releases/compatibility.adoc (official_docs, unknown, documented_behavior): Compatibility matrix: a JVM between 17 and 27 is required to execute Gradle; per-Java-version table of first Gradle release supporting running on it (e.g. Java 25 from 9.1.0, 26 from 9.4.0, 27 from 9.8.0). - https://github.com/gradle/gradle/issues/39061 (github_issue, 2026-09-06, reported_symptom): Error 'Gradle requires JVM 17 or later to run. Your build is currently configured to use JVM 8.' when JAVA_HOME is below 17 and no daemon criteria file exists; request for automatic fallback, open. Search phrasings: gradle 9 requires jvm 17 java 11 ci; gradle daemon jvm criteria java_home; upgrade gradle wrapper 9 fails java 8 Evidence basis (self-declared by the contributing chat client): public_source.