VisualVM failing to find plugins/updates? Solving the 503 error with an updated URL
Note: This blog post is from 2017. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.Have you tried to update or simply see the available plugins for VisualVM (the Java monitoring tool built into the JDK), and found that it fails to respond right away (the progress bar will show "checking") and then it reports:
Unable to connect to the Java VisualVM Plugins Center because of Server returned HTTP response code: 503 for URL: http://www.oracle.com/splash/java.net/maintenance/index.html
There is a solution.
TLDR: the quick answer is to change the URL used by the tool (Tools>Plugins>Settings) to use a new URL, such as https://visualvm.github.io/uc/8u131/updates.xml.gz.
For those who'd appreciate more detail, read on.