Hi @cansu tosun ,
Must tell you that our current Microsoft Q&A community only support English. Please post your question in English. Since the issue is windows related, I added the windows tag.
Through machine translation, I learned that you are installing windows 10 but it is not accepted the product key windows 8 installed, please clarify if there is any misunderstanding.
As fa as I know, perhaps the wrong edition was installed. If windows 8 was pre-installed by the manufacturer, then Windows 10 should probably be Windows 10 Home. Please type command winver in Search and check which version you have installed.
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