How to update Windows 11 to 25H2 manually from old windows version?

Download the Windows 11 25H2 ISO. This is the most tricky part as it is not public available yet. After that, use the WinUpgradeMate app to complete the upgrade. It supports any PC and no data loss:

https://www.wintechhow.com/upgrade-to-windows-11-25h2-without-data-loss

This is a very common situation. Since your computer is equipped with an Intel Core i5-6500 processor, which is an officially unsupported model, it cannot automatically receive the 25H2 update via Windows Update. The good news is that you can update Windows 11 to 25H2 manually.

1. Visit the official Microsoft Windows 11 download page. Select Download Windows 11 disk image → Windows 11. Choose your language, click Confirm, then select 64-bit Download.
2. Save important files to an external hard drive or cloud storage to prevent loss.
3. Right-click the downloaded ISO file and select Mount. A virtual drive will appear.
4. Open the virtual drive and double-click setup.exe.
5. When the This PC cannot run Windows 11 message appears, press Shift + F10 to open Command Prompt. Enter the code below, replacing 0 with 1.
6. Press Enter, then close the Command Prompt.
7. Click the back arrow (←) in the top-left corner of the installation window, follow the prompts, and wait through multiple reboots to complete the upgrade. After logging in, you'll be on the 25H2 version.

Following these steps will safely and successfully upgrade your Windows 11 laptop to the latest version.

Because your processor isn't officially supported, even if you manage to update Windows 11 to 25H2 manually, there could be stability or compatibility issues afterward. Microsoft’s official stance is to support specific hardware configurations, so proceed with caution and back up your data.

How to update Windows 11 to 25H2 manually:

1. Windows Update for Business or WSUS:
   If this is a corporate or managed device, sometimes updates can be pushed through organization channels. You can consult your IT administrator.
2. Using the Media Creation Tool or ISO (without registry edits):
   You mentioned avoiding registry edits and bypasses, so the most straightforward way remains updating via Windows Update. Since your system isn't receiving the update automatically, this indicates compatibility checks are preventing the upgrade.
3. Check for Optional Updates:
   Sometimes, feature updates like 25H2 are available as optional updates. Go to:
   Settings > Windows Update > Advanced options > Optional updates
   and see if the update appears there.
4. Ensure Your Windows is Fully Up-to-Date:
   Sometimes, installing the latest cumulative updates can trigger the availability of feature updates.

Step-by-Step Guide to Update to Windows 11 25H2 Manually:

• Visit the Microsoft Windows 11 Download Page.
• Scroll down to Download Windows 11 Disk Image (ISO).
• Select Windows 11 and click Download.
• Choose the latest version (which includes 25H2 if available), and download the ISO file.
• Use Media creation tool to create a bootable USB:
• Since your CPU isn't supported, you'll need to bypass the TPM, Secure Boot, and CPU checks.
• Download and prepare the ISO.
• Mount the ISO by right-clicking and selecting Mount.
• Run the Setup.exe from the mounted ISO.
• When prompted, do not proceed immediately.
• Continue with the in-place upgrade process.
• Windows should now proceed without blocking due to unsupported hardware.

About updating to Windows 11 25H2 manually, if you're uncomfortable with registry edits or bypassing checks, consider installing Windows 10 or using a clean install with an ISO, but be aware of the hardware limitations.

Windows 11 Installation Assistant is officially launched by Microsoft to force trigger feature updates on demand, and for most people, choosing this tool for manual system updates is the easiest option.

 How to update Windows 11 to 25H2 manually

1. Open Microsoft's official Windows 11 download page, and under the Windows 11 Installation Assistant section, click Download Now.
2. Locate the downloaded Windows11InstallationAssistant.exe file and run it, then accept the license terms.
3. The Installation Assistant will check your device's hardware compatibility, then download the 25H2 update package and start the installation; the screen will flicker and the computer will restart several times, which may take more than an hour.

Note: Be sure not to interrupt the process, the computer will restart automatically; after the update is complete, you will be automatically logged into the Windows 11 25H2 version, and all files and applications will be retained.

Given your situation—your laptop is running Windows 11 23H2, your CPU (Intel Core i5 6500) is not officially supported by Windows 11, and you want to update Windows 11 to 25H2 manually—that's a bit more complex. 
Important Consideration

• Since your CPU isn't officially supported for Windows 11, some features (like Windows Update) might be blocked. 
• Updating manually can still be done, but it may involve bypassing certain hardware checks, which can impact stability or security. 
• Proceed at your own risk and backup your data beforehand.

To update Windows 11 to 25H2 manually, some community tools/scripts (like UUB Dump or Windows11SysPraap) automate bypassing checks, but they carry risks and are more complex.