i updated to windows 10 now when i try to update itunes it says unvailed signature how do i fix this issue

If you have difficulty downloading the iTunes installer file try; unticking the "Keep me up to date..." box, clearing your browser's cache, changing pop-up blocker settings, right-clicking or ctrl-clicking the download button, using an alternate browser, or using the direct links from here.

See Troubleshooting issues with iTunes for Windows updates if you have any further trouble with the installation.

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