Debian – how to resume GRUB2 upgrade apparently blocked by /boot filesystem type=ext2

details

As detailed here, the /boot on this Debian Jessie had filesystem type=ext2

$ mount | grep -e '^/dev/'
/dev/sda3 on /boot type ext2 ...
...

and was unable to upgrade its GRUB2

$ sudo apt-get dist-upgrade 
...
Setting up grub-common (2.02~beta2-22+deb8u1) ...
Setting up grub2-common (2.02~beta2-22+deb8u1) ...
Setting up grub-pc-bin (2.02~beta2-22+deb8u1) ...
Setting up grub-pc (2.02~beta2-22+deb8u1) ...
Installing for i386-pc platform.
Installation finished. No error reported.
Installing for i386-pc platform.
grub-install: warning: File system `ext2' doesn't support embedding.
grub-install: warning: Embedding is not possible.  GRUB can only be installed in this setup by using blocklists.  However, blocklists are UNRELIABLE and their use is discouraged..

At about this point, my console went to a curses TUI to present a dialog with title=Configuring grub-pc and body telling me that GRUB failed to install:

Do you want to continue anyway? If you do, your computer may not start up properly.
Writing GRUB to boot device failed - continue?

I hit button=No. At that point,

• the GRUB2 packages={grub-common, grub-pc, grub-pc-bin, grub2-common} were installed (per apt-get and aptitude) but not fully configured (per message above).
• I had the following

questions

1. Should I now should update my {/dev/sda3, /boot} from filesystem type=ext2 to something else (presumably ext4)?

If I am misunderstanding the situation: what do I need to know? Is there something I should do to debug?

If I am not misunderstanding: what's the {easiest, most reliable, least disruptive} way to convert /boot's filesystem, on Debian (which this box is running)? fstransform?

2. Should I should now reconfigure GRUB2? E.g., how do I (or another Debian user in same situation) recreate the Setting up actions (see second text block) induced by the package install?

answers

1. It seemed clear to me that I should update my {/dev/sda3, /boot} from filesystem type=ext2 to ext4, which I did with fstransform (installing its Jessie package as detailed here. This seemed to go well (except for one problem).

However this filesystem upgrade may not have been necessary, per Jordan Uggla here.

2. Per Uggla's post, I reconfigured GRUB2 with sudo dpkg-reconfigure grub-pc --frontend=text as detailed here.

I now see and boot to the updated kernel and have no boot-time error messages.