1, You mean that you have upgraded your SCCM from 2012 to 2203, right? This is a similar threader, the OP said if you have a DNS or have disconnected from the public internet you will get his odd error.
The similar threader for your reference:
https://www.reddit.com/r/SCCM/comments/vp1krj/site_version_is_past_end_of_support_on_new/
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2, Besides, it seems the others have also encountered this problem, some people fixed it by upgrade the SCCM to the latest version. All support ends after the 18-month lifecycle has expired for a current branch version.
3, If the above methods cannot help you, it is recommended to open a support case with Microsoft Customer Support Services (CSS) as they can work with you to solve this problem.
Here is the link of CSS support:
https://support.microsoft.com/en-us/hub/4343728/support-for-business
Thanks for your time.
Best regards,
Cherry
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