[android-studio] How can I fix "Design editor is unavailable until a successful build" error?

  1. First, find your build.gradle in your all modules in project, include app/build.gradle. Find the compileSdkVersion inside android tag, in this case, compile sdk version is 30:

In this case, SDK version is 30

  1. Next, open SDK Manager > SDK Platforms, check correct version then install selected platforms. After installed, go to menu File > Sync project with Gradle files....

Install the API version which module requires

This issue often appear when project has many modules, each module use different compile SDK version, so app may be able to build but IDE have some issue while processing your resources.