Grub error: symbol “grub_calloc” not found. Entering rescue mode… grub rescue.

Since this morning, when i start my laptop, i only see the text:

Grub error: symbol "grub_calloc" not found.
Entering rescue mode...
grub rescue>

I recently updated the packages on my Ubuntu laptop.
I’m guessing it has something to do with the updates for the vulnerability “boothole” in Grub2.

I found this additional information:

working on this now….

because my laptop is not by default suited for Ubuntu <= 18.04 (did not test on >= 20.04) (because of a video card driver issue).
i could not use the default boot / install USB approach. (installed Ubuntu originally by use of the CLI).

the solution i used for most physical systems is: Boot-repair and running the “recommended repair”.

UUID storage in MySQL


You can store a UUID safely as a “Binary 16”, instead of a “Varchar 36”.

If you still require a human-readable column, its possible to use a “generated” column (from MySQL 5.7 and up):


additional info for MySQL 8.0 –