Hello @Rishant Jayaswal ,
Welcome to Microsoft Q&A forum.
The error message indicates that operation not permitted, perhaps it’s blocked by permission limitation. Please find the file(s) that mentioned in error message, right-click the file, select Properties, switch to Security tab, select the corresponding user, click Edit…, confirm that the account has been assigned the proper permissions.
Try to reboot your machine and directly open VS Code and install the extension(in case the file is locked by other program/process).
Besides, is there any permission limitation on your machine? Are you using any antivirus software/extension/proxy? If so, please try to disable them temporarily and test again.
Best Regards,
Tianyu
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