The error AADSTS5000225: This tenant has been blocked due to inactivity means the Microsoft Entra tenant behind the Azure trial has been marked inactive and blocked.

Key points from the tenant lifecycle behavior:

• When a tenant is blocked due to inactivity, sign-in to Azure (and services using that tenant) fails with this exact error.
• Administrators can request reactivation only within 20 days of the tenant entering the inactive state.
• After 20 days in this blocked state, the tenant is permanently deleted and cannot be recovered.

Actions depend on how long the tenant has been inactive and what role is available:

1. If the tenant has been inactive less than 20 days and there is an admin account
   • The tenant administrator must contact Microsoft using the global support phone numbers listed under “Administrators” in the tenant-inaccessible guidance: see the “Tenant inaccessible due to inactivity” article and use the global support phone numbers.
   • Only one assistance request should be submitted; wait for Microsoft’s decision before opening another.
2. If the tenant has been blocked more than 20 days
   • The tenant is deleted and is not recoverable. In this case, a new tenant and a new Azure subscription must be created; the old trial tenant cannot be reactivated.
3. If the issue is with an Azure for Students trial
   • If the 12‑month credit expired, the Azure for Students subscription is disabled. To continue using Azure, it must be upgraded to a pay‑as‑you‑go subscription by contacting Azure support.
   • If the Azure for Students subscription was accidentally canceled, it can be reactivated by contacting Azure support; remaining credit and free services are still available within the original 12‑month period.
4. Workarounds seen in similar trial scenarios
   • Some users with blocked free tenants have:
     • Cleared all browser data and signed in again, or
     • Opened an InPrivate/Incognito window and gone to the Azure signup page (https://signup.azure.com as shown in the context) with the same email. In those cases, the system recognized an existing free account and required an upgrade to a pay‑as‑you‑go subscription before access resumed.
   • If the tenant itself is already blocked due to inactivity, these steps may not help unless the tenant is still within the reactivation window and Microsoft support unblocks it.
5. If no reactivation path is available
   • If the tenant is past the 20‑day blocked window or Microsoft confirms it cannot be reactivated, the only option is to create a new Azure subscription (and, if needed, a new Microsoft account/tenant) and use that for Azure training.

For immediate next steps:

• Determine whether the tenant has been blocked less than 20 days.
• If yes and an admin account exists, contact Microsoft using the global support phone numbers for tenant reactivation.
• If it is an Azure for Students trial, or if billing/subscription status is involved, open a support request from the Azure portal support blade (if accessible) or via the Azure support links in the context to request upgrade/reactivation.
• If Microsoft confirms the tenant is deleted or outside the reactivation window, register a new Azure subscription for continued training use.

References:

• Tenant inaccessible due to inactivity
• Reactivate a disabled Azure subscription
• Why is my Azure for Students subscription disabled and how do I reactivate it?
• Error message: AADSTS5000225: This tenant has been blocked due to inactivity. - Microsoft Q&A
• 7 Day Old Azure Account: AADSTS5000225: This tenant has been blocked due to inactivity. - Microsoft Q&A
• Error message: interaction_required: AADSTS5000225: This tenant has been blocked due to inactivity - Microsoft Q&A
• Can not access Azure - Microsoft Q&A