Q: Bootcamp shows Windows 7 instead of 10 option on supported MacBook Air (11-inch, Mid 2013)

you can't download the iso or ?

Please post the MD5sum of the ISO file. It was corrupted during the download. If a wireless connection was used to download the ISO, please try a wired connection.

It is better to unmount the ISO, if it is mounted.

In your images above, Bootcamp assistant states that it only supports Windows 7 or later. This includes Windows 10, it's fine.

BCA is working fine, but it doesn't like your ISO.

Did you open the ISO after you downloaded it? It may be mounted as LonerT suggests.

Either unmount it, or restart the Mac and try the BCA again.

If that doesn't work, wait for an MD5 verification.

VimesTom wrote:

 

So, here's the md5:

MD5 (Win10_1511_2_English_x64.iso) = 3ca03a2c59ae5b58ca965a345d4f2ae1

I get the same MD5sum...

openssl md5 Win10_1511_2_English_x64.iso

MD5(Win10_1511_2_English_x64.iso)= 3ca03a2c59ae5b58ca965a345d4f2ae1

ls -lgh Win10_1511_2_English_x64.iso

-rw-r--r--@ 1 staff   4.2G May  7 08:33 Win10_1511_2_English_x64.iso

Can you run the following two procedures and try to use two W10 ISO? You may want to move the ISO to Documents and leave it unmounted?

Reset the System Management Controller (SMC) on your Mac - Apple Support

How to Reset NVRAM on your Mac - Apple Support

Please remember to back up OSX, Windows and create a Windows System Restore point. Regular backups are strongly recommended and encouraged.