boot camp usb There is not enough space available on the disk.

Thanks for your help, so far. So, I created a Sierra installer disk, created a startup Sierra USB, started up in Sierra, and am trying to run Boot Camp Assistant, putting a Windows 10 iso on an 8gig Kingstonl. Get the same error message. Not enough space. Get thru Formatting Selected Drive. Then says Your bootable USB drive could to be created. There is to enough space available on the disk. Any other ideas?

Here are the results:

Marks-Durango-iMac:~ Skywaterbanjo$ ls -lgh Win10_1803_English_x64.iso

-rw-r--r--@ 1 staff
2.9G May
6 12:54 Win10_1803_English_x64.iso

Marks-Durango-iMac:~ Skywaterbanjo$ openssl md5 Win10_1803_English_x64.iso

MD5(Win10_1803_English_x64.iso)= 4aea3f1928b1ecbbf55f306a0f4770c4

I redownloaded, tried the Bootcamp Assistant, received the same error of not enough space (trying still on an 8gb USB. Was attempted under Sierra, not High Sierra. Here is the output of the MD5:

Marks-Durango-iMac:~ Skywaterbanjo$ ls -lgh Win10_1803_English_x64.iso

-rw-r--r--@ 1 staff
3.5G May 11 02:21 Win10_1803_English_x64.iso

Marks-Durango-iMac:~ Skywaterbanjo$ openssl md5 Win10_1803_English_x64.iso

MD5(Win10_1803_English_x64.iso)= 82e3dac1a0ce3c69afc0db40c1150cc2

Marks-Durango-iMac:~ Skywaterbanjo$

The problem is probably that I have a very poor internet connection at my house. I'm going to try to download Win8 and see if I can get that installed and then do an upgrade. Either that or wait until I can be someplace with a more reliable connection. Should my MD5 checksum look the same as the one you posted?

iMac (21.5-inch, Late 2013)

Thanks for looking at this.

When I try to open the Sierra installer it says "this copy of the Install macOS application is too old to be opened on this version of macOS"

Filename: Win10_1803_English_x64.iso

how do I get MD5sum?

Does this mean I am not able to download a complete copy? Any other suggestions?

Thanks again for your help Loner!