testing on Safari 15.4, even browser.webNavigation.onCompleted also behaves unstably It can get non zero tabId, but can still return zero tabId sometimes. My test procedure open a new tab go to foo.com close the tab Repeat 1~3 many times, it looks like the first time onCompleted callback still return 0 tabId However I also encountered that some website always return 0 tabId no matter how many times I try Because of the unstable results, it indeed brings quite some hassle and confusion. The root cause is also unclear, it works for some website but not for others, is it related with the website itself? or my safari settings? or even my machine's settings. Hopefully it can be fixed or documented.

Created a feedback here https://feedbackassistant.apple.com/feedback/10022359 Thanks!

Hi, Sorry to bring up this old thread again, but is there any update or decision about Safari MV2 deprecation time line? like the Chrome document https://developer.chrome.com/docs/extensions/migrating/mv2-sunset/, It would be very helpful for WebExt developers to prioritize their work Thanks!