I'm trying to run the 3.0 emulator for macOS on a HighSierra mac. I had previously installed the 2.3 emulator, so:
I did a hard reset
I installed the new 3.0 emulator
I restarted the mac
Now, when I select Emulator in the Connect menu, I see a dialog saying "Starting the Android emulator. Please wait: this might take a minute or two" forever. Apparently there is no activity at all, except for an (empty) Terminal window appearing in the dock.
I successfully installed the 3.0 Emulator on Catalina and BigSur.
This will run aiStarter in the terminal. From App Inventor, try starting the emulator, and you will see some information logged into the terminal. Please copy and paste that here.
Once you've done that, press Ctrl+C to kill aiStarter. You can restore normal behavior by running:
Thanks @s_federici. Can you also send me the system information report on the device? To do this, open the menu, press down the Option key, and select "System Information..." when it appears. From the System Information window, select File then Save. I believe you already have my email address so just send it to me as an attachment.
The key error is:
emulator: ERROR: x86 emulator currently requires hardware acceleration!
Please ensure Intel HAXM is properly installed and usable.
CPU acceleration status: HAXM is not installed on this machine
so either the system doesn't support the virtualization technology required by the newer emulator, or something went wrong in the installation process. Once I have the information about the hardware I can advise on next steps.
Sorry for the late feedback. I managed to finally test the installation of the tool you suggested (I'm assisting a student of mine, that still uses HighSierra). The installation went fine, the student updated the security settings and restarted the mac. The emulator is not starting yet, still showing the message "Starting the Android emulator. Please wait: this might take a minute or two".
After that, they should be able to connect by using the Connect > Emulator option. The aistarter tool will use the existing emulator process from Android Studio rather than starting its own copy.
I use this method to test App Inventor on many versions of Android, so it should work for your student (assuming there isn't a hardware issue preventing the Android Studio emulator from working).
While waiting for the student to try the Android studio emulator strategy, I had another student that tried to run the InteHAXM installation and got the following error message
VT/NX not present Your computer does not meet the minimal requirements for this software. Intel(R) HAXM cannot be installed on this computer. Please refer to the Intel(R) HAXM documentation for more information
This worked very well on my Catalina mac. The emulator is already setup, right after installing Android studio. I had just to drag the companion to the emulator and connect the emulator. I hope the same smooth process can be applied to MacOS HighSierra. I will let you know how it goes.