Can't upload patch to 9.12.1 simulator

I need to patch my 9.12.1 simulator to get around the CIFS/Windows authentication issue (https://kb.netapp.com/Support_Bulletins/Customer_Bulletins/SU530#)

I've managed to get hold of the P7 patch, and when I first tried to upload it to the sim via the GUI (Cluster->overview->: More->Update ONTAP) I got an error message telling me there wasn't enough space.

I followed the instructions here:  https://kb.netapp.com/onprem/ontap/dm/System_Manager/System_Manager_fails_to_upload_ONTAP_image_due_to_insufficient_space

and now the upload directory has 2.9GB free, which should be ample (the P7 patch is only 2.3GB).

However, now when I try to upload the patch, the cluster just unceremoniously reboots. In the event log all I can see is mention of a coredump being saved, but nothing about what caused it.

I have expanded the RAM to 16GB, no difference.