How to install Windows 11 on ThinkPad T420 laptop?

If you're unable to install Windows 11 on a ThinkPad laptop, it could be due to several reasons, primarily related to ​​hardware compatibility​​ or ​​software restrictions​​. Here are the most common causes and solutions:

​​1. Your ThinkPad Doesn't Meet Windows 11 Minimum Requirements​​

Windows 11 has stricter hardware requirements than Windows 10. Check if your ThinkPad meets these:

​​CPU:​​ Must be an ​​8th Gen Intel or AMD Ryzen 2000 series or newer​​ (some 7th Gen Intel CPUs are supported but rare).
​​RAM:​​ At least ​​4GB​​ (8GB recommended).
​​Storage:​​ ​​64GB​​ or more.
​​TPM:​​ ​​TPM 2.0​​ must be enabled (some older ThinkPads have TPM 1.2 only).
​​Secure Boot:​​ Must be enabled in BIOS.
​​UEFI Mode:​​ Must be set (not Legacy/CSM).

2. TPM 2.0 is Disabled or Missing​​

Many ThinkPads have TPM, but it might be disabled in BIOS. How to Enable TPM 2.0:​​

1. ​​Restart​​ your ThinkPad and press ​​F1​​ (or ​​Enter → F1​​) to enter ​​BIOS​​.
2. Go to ​​Security → TPM 2.0​​ (or ​​Security Chip​​).
3. Enable ​​TPM 2.0​​ (or "Security Chip").
4. Save & Exit (​​F10​​).

If your ThinkPad has ​​TPM 1.2 only​​, it ​​won’t officially support Windows 11​​.

3. Secure Boot is Disabled​​

Windows 11 requires ​​Secure Boot​​ enabled in ​​UEFI mode​​. How to Enable Secure Boot:​​

1. Enter ​​BIOS (F1)​​.
2. Go to ​​Security → Secure Boot​​.
3. Set it to ​​Enabled​​.
4. Ensure ​​Boot Mode​​ is ​​UEFI​​ (not Legacy/CSM).
5. Save & Exit (​​F10​​).

4. BIOS is Outdated​​

Some older ThinkPads need a ​​BIOS update​​ to enable TPM 2.0 or Secure Boot properly. ​​How to Update BIOS:​​

1. Go to ​​Lenovo Support​​ (support.lenovo.com).
2. Enter your ​​ThinkPad model​​ (e.g., ​​T480, X1 Carbon 6th Gen​​).
3. Download the latest ​​BIOS update​​.
4. Run the installer and follow instructions.

Those suggestions are good solutions to help you install Windows 11 on Thinkpad laptop.