The widespread use of code from Facebook maintained React.js, a popular developer tool for building interfaces with JavaScript, is the reason why this issue is particularly problematic for Apache. Unless Facebook changes the license, all of Facebook’s code will have to be removed from all projects that have been using it. In some cases that might be impossible, meaning popular applications will no longer be available. In July, when Apache became aware of the problem and declared the license off limits, it was widely hoped that Facebook would relent and either rewrite the license or adopt a new one.