Apps
Java Runtime Cache
Java Runtime Cache stores downloaded Java Web Start and legacy applet resources on disk so they do not need to be fetched and verified every time. It typically contains cached JAR files, JNLP launch descriptors, native library extracts, icon assets, and deployment metadata created by the old Java deployment subsystem. Kudu removes these temporary deployment cache files so stale launch resources and corrupted downloaded components can be rebuilt without affecting installed Java runtimes, user files, saved credentials, or application settings.
Why clean Java Runtime Cache?
- An outdated cached JAR or JNLP file can survive after the server has published a newer version, causing Java Web Start apps to launch the wrong build or fail with version mismatch errors
- Corrupted deployment cache entries often show up as launch failures, endless 'Downloading application' prompts, or security verification errors even though the app works for other users
- Stale extracted native libraries in the cache can conflict with a newer app update and produce startup crashes, missing DLL or .so errors, or immediate window closure after launch
- Repeatedly downloaded applet and Web Start resources accumulate in the deployment cache over time, wasting disk space long after those legacy apps are no longer used
- Expired or inconsistent cached signing metadata can trigger certificate warnings, blocked application dialogs, or prompts to trust the same publisher again on every launch
- Partially downloaded JARs left behind after a network interruption can cause frozen splash screens, checksum failures, or apps that never get past initialization until the bad cache entry is removed
What gets cleaned
Cache paths Kudu targets
Windows
~/AppData/LocalLow/Sun/Java/Deployment/cache |
macOS
~/Library/Application Support/Oracle/Java/Deployment/cache |
~/Library/Caches/Java |
Linux
~/.java/deployment/cache |
Frequently asked
Common questions about Java Runtime Cache
Related cleaners
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Available on Windows, macOS, and Linux. No account required, no feature gates, no telemetry without consent. All cleaning targets are open source and community-auditable.