Because the category is "Download Error," the system likely failed to reach the server.
: Open your Java Control Panel , go to the General tab, click Settings under Temporary Internet Files, and click Delete Files . Ensure you select "Applications and Applets" and "Trace and Log Files." 2. Check Network and Server Connectivity
Java Web Start is extremely strict about security. If your application uses multiple JAR files, they must all be . Help with understanding JNLPException - Oracle Forums Because the category is "Download Error," the system
Below is a guide to the most common causes and how to fix them. 1. Clear Your Java Cache
A corrupted local cache is the most frequent cause of "null" exceptions. If Java thinks it has a file but the file is incomplete or corrupted, it may fail silently. Check Network and Server Connectivity Java Web Start
: Ensure your Java settings aren't forced into "Offline Mode," which prevents the downloader from fetching updates.
: If you are a developer, double-check that the codebase attribute in your JNLP file accurately reflects the server's URL. If the codebase is wrong, the launcher won't find the associated JARs. 3. Verify JAR Signing and Certificates it may fail silently.
: Verify you aren't behind a firewall or proxy blocking the .jnlp or .jar extensions.
