Hello @Ehsan Gheysar,
Thank you for reaching out to Microsoft Q&A.
We understand that you are facing an issue when you are trying to enroll your devices to Entra ID to control. You are being prompted with an error 0x801c03f2 while you are registering the device. Further, you have also noticed the server message stating that “$expand links is not supported for mega tenants”. The error code 0x801c03f2 typically indicates a directory error during the device registration process with Microsoft Entra ID. Considering this error “$expand links is not supported for mega tenants” a mega tenant will typically refer to B2C/MSA tenants in the scope of Azure. Unfortunately, device registration directly with Azure AD B2C (Microsoft Entra B2C) is not supported, as Azure AD B2C is primarily designed for managing customer identities and access.
Sharing relevant document for more information: https://learn.microsoft.com/en-us/entra/identity/devices/troubleshoot-hybrid-join-windows-current#step-3-find-the-phase-in-which-the-join-failed-and-the-error-code
Hope this helps. Do let us know if you any further queries.
Best Regards
Janaki Kota