Last week Microsoft released build 10130 of Windows 10 for Windows Insiders on the fast ring and Microsoft have took the unusual step of releasing this build as an ISO but not pushed it to the slow ring. The reason it has not made the slow ring it has a number of bugs in it including a WiFi issue but Microsoft have decided to release 10130 as an ISO due to a 0x80146017 error many insiders have had preventing them from installing it.
Details from the Windows Blog:
Hi everyone, today we are releasing the ISOs for Windows 10 Insider Preview Build 10130. We are not, however, releasing Build 10130 to the Slow ring due to several bugs we’re looking to fix. Once we have these fixes in hand and ready to push out to Windows Update, we’ll consider pushing Build 10130 to the Slow ring. I know we said we would only release ISOs if we push a build to the Slow ring but we’re making a special exception today. We know that a bunch of Windows Insiders on the Fast ring are currently blocked getting to the latest build due a 0x80146017 error. With the ISOs, they can mount the image and upgrade directly from the ISO and get unblocked