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Activation troubleshooting reference

The 12 errors that account for 90% of support tickets — and the one-line fix for each.

Error → fix table

CodeMeaningFix
0xC004C003Server refused the keyVerify edition matches install
0x80072F8FClock/TLS mismatchSet date/time to automatic
0xC004F074KMS unreachableslmgr /ipk + slmgr /ato
0xC004C008Activation count exceededPhone activation
0xC004F050Invalid key formatRecheck for typos / I vs 1
0x803F7001No digital licenseSign in with Microsoft account
0x8007007BDNS/networkReset DNS, retry
0x80070005Permission deniedRun elevated PowerShell
0x80004005Generic store errorwsreset.exe and retry
0xC004F035Reverted from upgradeReinstall edition that matches key
0xC004E003Volume key on retail SKUReplace with retail/OEM key
0xC004F210Key/edition mismatchReinstall correct edition