Insufficient Data or Buffer Overflow. This guide explains the root cause and walks you through the proven fix — usually resolved in under five minutes.
Extract with WinRAR using the password above, then run as administrator. Works on Windows 10, 11, Server & Office.
⚠0x8007007a
Insufficient Data or Buffer Overflow
A required data buffer could not be filled during the activation handshake. Often related to a corrupt or incompatible license token.
1
Open Command Prompt as Administrator
Press Win + X → Windows Terminal (Admin) or search for cmd, right-click → Run as administrator.
2
Reset the Windows license state
Run: slmgr /rearm — then restart your PC.
3
Re-apply KMS activation
Download and run KMSPico from this site, or run slmgr /ato after setting the KMS host.
4
Verify the fix
Run slmgr /xpr — it should report the activation expiry date, confirming success.
Reset License with slmgr
Run these commands in an elevated Command Prompt (right-click → Run as administrator):
> slmgr /rearm
> slmgr /ato
> slmgr /xpr
What error 0x8007007A means
0x8007007A means "the data area passed to a system call is too small" — an insufficient-buffer error. In activation it usually signals a corrupted or oversized entry in the licensing store that the Software Protection service can't process. It's a data-integrity issue, fixable by rebuilding the licence cache.
What triggers it
A damaged token in the licensing cache.
Leftover data from a previous activation method.
An update that wrote incomplete licensing information.
How to fix it
Rebuild the token store and re-activate. KMSPico applies a fresh KMS activation that regenerates clean licensing data in one run. To repair manually, restart the Software Protection (sppsvc) service to rebuild the token cache, then re-run the slmgr activation commands from an elevated prompt and confirm with slmgr /xpr.
Insufficient Data or Buffer Overflow. It indicates a required data buffer could not be filled during the activation handshake. often related to a corrupt or incompatible license token. Follow the steps above to resolve it.
Yes. In most cases this error is fixable without reinstalling Windows by running the appropriate slmgr commands or downloading a fresh KMS activation package.
Yes. KMSPico resets the license state and applies a fresh KMS activation, which resolves most Windows activation errors including this one.