Gatekeeper quarantine issue with certificate
Our Although our app is code signed . Our Apple and apple certificate is up to date. Previous versions of our app have run just fine.However, when the DMG is downloaded by the users, on some Macs the application is quarantined, but for the majority of users, it's not. So some users can open the app and others get the "X.app can’t be opened because the identity of the developer can not be confirmed.", we sometimes run into issues as shown below .
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Explanation
When you download a file with a browser, the browser will attach a com.apple.quarantine attribute to it, indicating that it came from an untrusted network source. Other types of internet apps (email, chat, etc) should also attach this attribute to downloaded files.
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In this case, when you download the .dmg file, it gets marked as quarantined; when you open it, the attribute gets propagated to its contents, so the app is also marked as being in quarantine.
The solution
There are two types of solution to fix this issue.
Solution 1(Preffered) :
Unmount the dmg file
open the terminal and execute the following command
xattr -d com.apple.quarantine </path/to/file>
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now remount the dmg file and you should not see the warning any more and the wizard should pop up as shown below
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Solution 2 :
Mount the dmg file and open it you should get the error screen as below. click ok
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Go to system Settings serach for security and you should see your application was blocked from use … click on Open Anyway
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Now it amy ask for a password, enter it and click on Unblock
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Now the next screen would appear. click on open
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Now the installation wizard should appear
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