Android Studio Emulator wont start “Waiting for target device to come online”

So I am currently learning how to develop android apps. I am making my first application and I have no errors but my emulator wont run my app. It is stuck on "Waiting for target device to come online". I am confused on what is wrong because It has worked before. I completely reinstalled everything and it still does not work. Not sure what to do.

Uncheck then recheck 'Enable ADB Integration' from the Android Studio 'Tools - Android' menu and it will work.

In my case I opened Android Studio and then, in the menu, navigated through Tools -> Android -> AVD Manager.

As seen at the image below, I had a message that "Android Emulator is incompatible with Hyper-V."

I have followed the steps suggested (as below):

Unfortunately, you cannot have Hyper-V running and use the emulator. Here is what you can do:

Start a command prompt as Administrator

Run the following command: C:\Windows\system32> bcdedit /set hypervisorlaunchtype off

Reboot your machine.

After the system reboot, I opened the same window (AVD Manager), and a next warning was available, to install HAXM:

After that, the emulator started, but very slow. The next suggestion was to install a better emulator using x86 which gives better performance in my machine (10x faster):

Google Play Intel x86 Atom System Image (system-images;android-24;google_apis_playstore;x86)

My case, I used to use android emulator well. But when I tried to run adb by Android Studio one day, it just showed 'waiting for target device ...', and the emulator disappeared suddenly.

After checking some, and then I knew that docker was the reason, I think Docker (or Docker Kinetics) and android emulator conflict together on osx (mac).

Turning off Docker, I can use android emulator as usual.

I ran into this same issue and the problem was that Quick Launch caused the emulator to get out of sync with the IDE/adb for some reason.

Here are the steps I took to fix the problem:

Close the emulator (if running).
Open the Android Virtual Device Manager (AVD Manager).
Click the dropdown arrow under 'Actions' (far right).
Select 'Cold Boot Now'.
After the Emulator boots back up, click Run app and select the running Emulator.

I solved this by turning off the emulator using the power off button, not using the close (x) button (avoiding saving emulator state message). Then launching again the emulator worked for me.

Jonothan's solution directed me this one and it worked for me as the one that Jonathan mentioned didnt work for my case.