Hi Abhijit,
It might be related to this:
Issues with building native apps for Android
Although the external repository seems to be online again, not all dependencies can be downloaded. Unfortunately, we can't remove the external repository, as some dependencies are not available anywhere else. We have asked the owners of the external repository to investigate why not all dependencies are available yet.
Dec 22, 11:40 CET
From:
https://status.mendix.com/history
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