问题
I am having the following problem when running or debugging apps on a device or emulator with Android Studio. The application is installed but it is not started on the device (or emulator). In the Run window I can see the following:
Launching app on device. Waiting for process to come online...
and after some time I see the following: Timed out waiting for process to appear on 'device'...
I have attached a screenshot that shows the problem.
The problem started recently. I am using the latest version of Android studio (3.5.1) and a Google Pixel device running Android 10 but the problem happens on emulators and other devices running previous versions of Android. The problem also happens on two different computers, with different Android applications and devices - the common factor is Android studio. Finally, the problem seems to have started after I updated Android Studio to 3.5.
Does anyone know how to fix this problem? I have tried many things (clear cache, rebuild, invalidate and restart, etc) without success.
Any ideas?
回答1:
There is a bug in the recent Android Studio release. You can revert to previous version or test it from command line.
回答2:
You mentioned that restarting Android Studio didn't work for you...but it worked for me...
File > Invalidate Caches / Restart... > Just Restart
Android Studio 3.6.2
Build #AI-192.7142.36.36.6308749, built on March 18, 2020
回答3:
Hey I had this same problem recently, I tried re-starting adb server but no luck, however when I uninstalled the APK present on my device. Then everything was back to normal.
When I tried to run it on a emulator which didn't have application already, it worked perfectly fine.
Hope this helps :) Thank You.
回答4:
For me the problem was that I accidentally removed the Launch of the Default Activity in the "Run > Edit Configurations..." option.
Just insert the "Default Activity" under "Launch Options" and your application will run again on your device.
来源：https://stackoverflow.com/questions/58245771/timed-out-waiting-for-process-to-appear-on-device