I am trying to install 25h2 on my pc but it does not install

Build 26100 is the Windows 11 24H2 branch, so first repair the Windows Update download failure and then verify that your Insider channel is offering a 26200-series 25H2 build.

1. Confirm the Insider update being offered

Microsoft’s Insider release notes identify:

• 26100.x as Windows 11 24H2
• 26200.x as Windows 11 25H2 ^1^

Open:

1. Settings → Windows Update → Windows Insider Program
2. Note the selected Insider channel. If you intend to install the published Release Preview version of 25H2, the PC must be enrolled in Release Preview.
3. Return to Settings → Windows Update.
4. Record the complete name and KB number of the failed update under Update history.

Build 26100.8772 itself is not 25H2. A successful 25H2 upgrade should change the OS build to the 26200 branch.

2. Run the Windows Update troubleshooter

Error 0x80070002 means that the update failed to install, but the code alone does not identify which file or component caused it.

1. Open Settings → System → Troubleshoot → Other troubleshooters.
2. Find Windows Update and select Run.
3. Apply any recommended repairs.
4. Restart Windows and check for updates again.

This is Microsoft’s first supported diagnostic for Windows 11 update failures. ^2^

3. Rebuild the downloaded update files

Back up important files before continuing. Deleting the contents below removes cached update downloads, not personal files.

1. Press Win+R, enter services.msc, and press Enter.
2. Right-click Windows Update and select Stop.
3. Open File Explorer and navigate to: C:\Windows\SoftwareDistribution
4. Delete everything inside that folder.
5. Return to Services, right-click Windows Update, and select Start.
6. Restart the PC, then open Settings → Windows Update → Check for updates.

Microsoft documents this procedure for rebuilding the Windows Update cache. ^2^

4. Repair Windows system files

If the download still fails, open Terminal (Admin) or Command Prompt (Admin) and run these commands in order:

DISM.exe /Online /Cleanup-Image /RestoreHealth
sfc /scannow

Wait for each command to finish. Restart after SFC reaches 100%, then retry Windows Update. Microsoft recommends DISM followed by SFC when damaged system components may be preventing updates. ^2^

If it still fails

Do not apply registry files or third-party repair packages intended for another computer. A closely matching 25H2 case had 0x80070002 because its CBS log showed a missing input.inf driver file, but that cause was established from that computer’s logs and cannot be assumed here. ^3^

Collect these details for the next diagnosis:

• Failed update’s complete name and KB number from Update history
• Selected Windows Insider channel
• winver screenshot or exact output
• C:\Windows\Logs\CBS\CBS.log
• Whether DISM and SFC reported corruption they could not repair

Also verify that the displayed build was copied correctly: Microsoft’s nearby Release Preview publication lists 26100.8728/26200.8728, whereas the stated build is 26100.8772. ^1^

References

1. Windows 11 Insider Release Preview Build 26100.8728/26200.8728
2. Windows 11
3. Windows 11 25H2 Update failing to install with error - Install error - 0x80070002 - Microsoft Q&A