Comment 27 for bug 1876157

I have the same issue on Ubuntu 20.04 LTS. There is some issue with the memtest86 binary in Ubuntu. Here is how to fix it:

1. Get rid of Ubuntu version of memtest
   sudo apt remove memtest86+

2. Download the official memtest86 5.01 binary from here : https://www.memtest.org/download/5.01/memtest86+-5.01.bin.gz

3. Extract from the archive and copy memtest86+-5.01.bin to /boot
    sudo cp memtest86+-5.01.bin /boot/memtest86+.bin

4. Update grub
    sudo update-grub