There is a problem with this Windows Installer package. A program required for this install to complete could not be run Contact your support personnel or package vendor.
iPhone 6 Plus, iOS 9.3.1
Troubleshooting issues with iTunes for Windows updates - https://discussions.apple.com/docs/DOC-6562
iTunes: Specific update-and-restore error messages and advanced troubleshooting - https://support.apple.com/HT204770
Typically that indicates that the old version of Apple Software wouldn't uninstall when it was asked to. Try repairing it from the Programs and Features control panel, then try installing iTunes once more.
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any other suggestions - that didn't work.
For general advice see Troubleshooting issues with iTunes for Windows updates.
The steps in the second box are a guide to removing everything related to iTunes and then rebuilding it which is often a good starting point unless the symptoms indicate a more specific approach. See the notes below regarding items that won't uninstall.
Review the other boxes and the list of support documents further down the page in case one of them applies.
The further information area has direct links to the current and recent builds in case you have problems downloading, need to revert to an older version or want to try the iTunes for Windows (64-bit - for older video cards) release as a workaround for installation or performance issues, or compatibility with third party software.
Your library and device backups should be unaffected by these steps but there are links to backup and recovery advice should it be needed.
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What does this mean?
