There are several reasons why you might get an error after entering a product key. For example, the product key may have been mistyped or a product key for a different product might have been used.

Are you entering a product key for another Microsoft product?

Most Microsoft products use a 25-character product key. If you own multiple Microsoft products, it’s easy to confuse the keys and use the wrong one. Here are some common things that can happen:

Using the product key from a sticker on a PC   

These product keys are normally for Microsoft Windows. Check the sticker for a product name to make sure it’s for the Office product you’re trying to install.

Using the product key from an earlier version of Office   

Office product keys aren’t interchangeable between Office versions. For example, you can’t use a Microsoft Office Home and Student 2007 product key if you’re trying to install Microsoft Office Home and Student 2010.

Using the product key from an individual program to install a suite   

Office product keys aren’t interchangeable between Office suites and individual programs. For example, you can’t use a Microsoft Word product key to install Microsoft Office Home and Student.

Using the product key provided by a school or company   

Schools and companies usually buy a different type of Office license. The product keys they provide to students, teachers, and employees are known as volume license keys. These keys can’t be used for retail Office versions like Home and Student, Home and Business, or Professional.

Did you mistype the product key?

Reading the product key from a label can be difficult. Letters and numbers may look the same.

To avoid typing mistakes, here’s a list of commonly mistyped characters:

The letter B and the number 8.

The letter G and the number 6.

The letter O and the number 0.

The letter Q and the number 0.

The letters V and V back to back (VV) appear like the letter W.

If you're having trouble reading the characters in your product key, here's an example of what the letters and numbers look like:

Tip: If you bought Office from an online retailer and received a confirmation email, try copying and pasting the product key from this email instead of typing it.

Is your product key still not working?

If your Office product key doesn’t work, or has stopped working, you should contact the seller and request a refund. If you bought a product key separate from the software, it’s very possible the product key was stolen or otherwise fraudulently obtained, and subsequently blocked for use. Unfortunately, there are many dishonest sellers who offer stolen, abused, or otherwise unauthorized Microsoft product keys for sale. Sometimes these product keys are printed on counterfeit labels or cards with a download link to Microsoft software, and sometimes they’re distributed with software media that is unauthorized for resale, such as promotional media, original equipment manufacturer reinstallation media, or other Microsoft program-specific media.