For JavaScript Bugs, please read this.

Bugs are a constant problem with software development. In HtmlUnit, there are several factors for the cause of bugs. These include: bugs in third-party code, functionality that still is not supported by HtmlUnit, bugs in your code, or true bugs in HtmlUnit. To track these bugs, we are using the GitHub issue tracking system located at

Before reporting an error, make sure that you are up to the latest version of the software. If you can, get the latest snapshot, or build it from the sources yourself to see if the error still occurs. Check the dependencies to be sure that you have all the required jar files. Also, review the list of bugs and recently closed bugs to see if someone else has already reported the bug. If they have, you may want to just add more detail to it.

How to submit reports that get responses

Development of HtmlUnit is done as a volunteer effort. As such, the developers respond when they get a chance. There are a number of things that you can do to help get a quicker response

  • Describe the bug in as much detail as possible. To be able to fix a bug, the developer has to be able to reproduce it. The more detail provided, the easier this is to do. Include the source code that you have to produce the bug and the HTML page. Reduce this down to the least amount of code required to produce the error on both the executing code and the HTML. If the developer has to look through 2 pages of HTML and JavaScript to see what is happening, it may not happen.
  • If you can, write a JUnit test that reproduces the error. This makes it much easier to find the bug since the developer has to just run the unit test to reproduce the error.
  • Best is to review the code and find what is causing the bug and not only write a unit test that produces the bug, but also a pull requests that fixes the bug. Include these files in the bug report following the rules for submitting pull requests.