After I upgraded our SCCM to 1702 and the ADK to 1703 the step for converting a device from BIOS to UEFI in our Windows 7 –> Windows 10 Task sequence started to fail with an 0x80070070 error. This had worked without any problems in SCCM 1610 with the 1607 ADK so what had changed?
When I set up the TS I followed the directions on the Microsoft docs page:
The step that describes how to set up formatting of the drives specifies that you need to create a FAT32 partition and that you need to choose GPT for Disk type.
The picture show that the FAT32 partition is 500MB and the rest of the disk is used for normal NTFS. This is the way I set it up too.
So what could be wrong? Error 0x80070070 translates into "There is not enough space on the disk". After a little troubleshooting by opening a command prompt during the TS when it failed I noticed that 500MB FAT32 partition was actually full.
So what does this partition really do you might wonder? Well for the computer to be able to survive a restart during the conversion process this partition holds the boot files from the boot image you are using in SCCM and also all TS/OSD related files.
It turns out that the boot image from ADK 1703 had increased with about 50MB compared to the boot image from the 1607 ADK, from approx. ~435MB to ~475MB. This together with the other files in the UEFI partition made it run out of space.
Reading the page on Microsoft docs once more made me realize that it didn’t actually say anywhere that the partition needed to be exactly 500MB, so after changing it to 600MB and trying once more everything worked great again!