"Couldn't upload. Try again." error on Google Play Console

When I try to upload my Android App Bundle to the Google Play Console, I get this generic error message saying "Couldn't upload. Try again.".

I've already tried:

• making sure my versionName and versionCode are unique among all uploaded artifacts
• making sure that the .aab/.apk is signed with the proper key
• re-uploading the .AAB file
• re-uploading the .APK file
• checking status of google services to make sure that there isn't a mass outage
• asking my senior Android dev what's up

How do I resolve this error and upload my .AAB or .APK?

Google Chrome

Use a new Incognito window to upload the .aab or .apk (as mentioned in the comments).

Alternatively, clear the website data:

1. going to: developer console (F12) > Application > Storage > Clear site data
   • Screenshot
2. press F5 to refresh the page
3. uploading the .apk/.aab again

Safari

Open Preferences > Privacy > Manage Website Data > Remove All > Done

Here's what worked for me: After getting the error on play console. Now use 'Add from Library' option instead of 'Upload', and you will find your appbundle that failed to upload there, select it and proceed with further steps.

This problem comes out due to multiple gmail logins on same browser, if the developer account is not the default logged in account. You can solve this by signing out all gmail accounts and login in the specific gmail account.