This error means that current gradle version doesn't support Java with version 12 , i traced logs , and found that UE4 try to use 4.6 version of gradle which really don't support my Java version , in order to solve you need to change file which UE use as template (to download gradle version). Here's file location UE_4.23\Engine\Build\Android\Java\gradle\gradle\wrapper\gradle-wrapper.properties. Update row where distributionUrl =... to distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.2-all.zip save file and try launch again UE will use this updates as template and in own turn dowload 5.6.2 version which support java version 11 , 12 .. and new grandle will build project.