问题
After I update android studio to 2.3, my old project is not opened in android studio shows me gradle error. And when I open a new project, that project is not build
回答1:
After the new update of android studio (2.3) this is a common bug.But heres the best solution to this.Once you get a message as gradle sync failed,then its as because your gradle file got bug. the solution is go to C:\Users\Admin.gradle\wrapper\dists\gradle-3.3-all\55gk2rcmfc6p2dg9u9ohc3hw9 here you can find a zip file : gradle-3.3-all.zip
delete all contents in that and download file from https://downloads.gradle.org/distributions/gradle-3.3-all.zip
paste this in 55gk2rcmfc6p2dg9u9ohc3hw9 folder. Then restart studio.It will be working perfectly.
If you have any other version of gradle you can find the corresponding file in https://services.gradle.org/distributions
回答2:
I found it my self now, its very easy Just need Edit "build.gradle.project" dependencies to 2.3.0 and edit file "gradle.wrapper.properties" , distributionUrl to "/gradle3.3-all.zip" and sync project
来源：https://stackoverflow.com/questions/42652078/gradle-connection-timed-out-after-update-android-studio-to-2-3