Windows 11 Upgrade Failed? Fix 0xC1900101 and Other Errors

You leave the PC to upgrade, come back, and find “Undoing changes made to your computer” or a message that Windows 11 could not be installed. A Windows 11 upgrade failed message is frustrating, but it is rarely a disaster: setup is designed to roll back to the previous version with your files intact. This guide explains how to read the error, the fixes that solve most failures, how to use Microsoft’s SetupDiag tool to find the real cause, and how to retry.

It applies to Windows 10 to Windows 11 upgrades and to moving between Windows 11 versions with a full upgrade.

First, do not panic

When an upgrade fails, Windows restarts into the previous version. Check that your desktop, documents and apps are as before. Then make a backup before you try again, so the next attempt carries no risk.

If you are on Windows 10, you are not in a hurry: Microsoft’s consumer Extended Security Updates program keeps enrolled PCs patched until 12 October 2027, according to its ESU page as checked on 14 October 2026. Enroll the PC if you have not, then fix the upgrade calmly.

Read the error code

Note the full code. You find it on the final setup screen, in Windows Update history (Settings > Update & Security > Windows Update > View update history on Windows 10), or in SetupDiag’s results.

Code	What Microsoft’s resolution guide says it usually means
0xC1900101 - xxxxx	Generic rollback code; usually an incompatible driver
0xC1900200 / 0xC1900202	The PC does not pass the minimum requirements to install or download
0x80070070 or 0xC190020E	Not enough free space to install
0xC1900208	The PC does not pass the compatibility scan; often an incompatible app
0xC1900107	Cleanup from an earlier attempt is pending; restart and try again

The part after the dash in 0xC1900101 shows the phase in which setup failed, for example during the first boot of the new system or during migration. Microsoft’s guide maps these to likely causes.

Fixes that solve most failures

Work through these, retrying after each group:

1. Drivers and firmware. Install all updates, including optional driver updates in Windows Update. Download the latest chipset, storage, graphics, Wi-Fi and audio drivers from the PC maker’s website, and update the firmware (BIOS/UEFI) if the maker offers a newer version. Outdated storage and graphics drivers are the classic 0xC1900101 culprits.

2. Disconnect peripherals. Leave only keyboard, mouse and display connected. Remove docks, USB drives, card readers, printers and external disks.

3. Third-party security software. Uninstall third-party antivirus, VPN and disk encryption tools temporarily. Microsoft lists removing antivirus as a mitigation for some failures. Windows Security protects the PC meanwhile. Reinstall afterwards.

4. Free space. Delete temporary files with Disk Cleanup or Storage Sense and move large files to another drive. See Windows 11 storage settings.

5. Repair system files. Open an administrator terminal and run DISM /Online /Cleanup-Image /RestoreHealth, then sfc /scannow. See SFC scannow and DISM RestoreHealth.

6. Clean boot. Microsoft suggests running setup with a minimal set of drivers and startup programs. Turn off startup apps (Task Manager > Startup apps) and restart before trying again.

Find the cause with SetupDiag

Microsoft’s SetupDiag is a free tool that analyses the log files setup leaves behind.

1. Download SetupDiag from Microsoft’s SetupDiag page on Microsoft Learn.
2. Save it to a folder such as Downloads and run it on the PC where the upgrade failed. Approve the administrator prompt.
3. When it finishes, open SetupDiagResults.log in the same folder.

The results often name a specific driver file or application. Update or uninstall that item, then retry. Microsoft’s guide also points to setup’s own logs when tracking down failing drivers: setuperr.log and setupact.log in C:\Windows\Panther, and rollback logs in the hidden $Windows.~BT\Sources\Rollback folder.

Check the hardware basics

Repeated failures at the same point can also come from hardware problems that only show under the heavy load of an upgrade:

• Disk errors: open an administrator terminal and run chkdsk C: /scan to check the file system online. If it reports problems, schedule a repair with chkdsk C: /f and restart. On an NVMe SSD, check its health as described in check SSD health in Windows 11.
• Memory errors: search for Windows Memory Diagnostic in Start and choose to restart and check for problems. Errors here mean faulty RAM, which no amount of software fixing will cure.
• Overheating: laptops that run hot can crash during long installs. Run the upgrade on a hard, flat surface with the charger connected.

Microsoft’s guide also lists multiple system partitions as a cause of some 0x8007xxxx errors, for example when an old system drive is still connected after fitting a new one. Disconnect the old drive during the upgrade.

Retry with a cleaner method

If Windows Update or the Installation Assistant keeps failing:

1. Download the Windows 11 ISO from Microsoft, in the same language as your installed Windows (ISO download guide).
2. Right-click it and select Mount.
3. Run setup.exe from the mounted drive, choose Not right now for updates if online updates seem to cause the failure, and select Keep personal files and apps.

This uses the same in-place process described in Windows 11 in-place upgrade.

When the PC is not eligible

Errors such as 0xC1900200 mean the hardware does not meet the requirements. Run a compatibility check to see which one. TPM and Secure Boot can often be enabled in the firmware; an unsupported processor cannot. We do not publish requirement bypasses: Microsoft says unsupported PCs are not guaranteed updates, including security updates.

Last resort

If every in-place attempt fails on an eligible PC, back up your files and do a clean install. It removes apps and settings but avoids whatever is blocking the upgrade. For failures of normal monthly updates rather than upgrades, see Windows 11 update failed.