mistranslation: 0.973
architecture: 0.962
x86: 0.931
device: 0.874
semantic: 0.783
arm: 0.742
user-level: 0.733
files: 0.733
graphic: 0.731
ppc: 0.664
PID: 0.603
network: 0.566
performance: 0.563
kernel: 0.546
debug: 0.545
i386: 0.540
permissions: 0.536
boot: 0.523
VMM: 0.431
peripherals: 0.421
socket: 0.420
risc-v: 0.417
register: 0.402
hypervisor: 0.400
TCG: 0.381
virtual: 0.365
vnc: 0.347
KVM: 0.267
assembly: 0.098
--------------------
x86: 0.980
user-level: 0.930
debug: 0.692
hypervisor: 0.589
files: 0.165
virtual: 0.150
register: 0.077
TCG: 0.049
device: 0.047
semantic: 0.015
kernel: 0.011
architecture: 0.009
PID: 0.007
permissions: 0.007
boot: 0.006
assembly: 0.003
network: 0.003
VMM: 0.003
peripherals: 0.002
socket: 0.002
KVM: 0.002
performance: 0.002
graphic: 0.002
ppc: 0.002
mistranslation: 0.001
risc-v: 0.001
vnc: 0.001
i386: 0.000
arm: 0.000

Wrong error log when drive is specified qcow but qcow2 image file used.

On archlinux qemu version 4.0.0 when I type:

$ qemu-system-x86_64 -drive format=qcow,file=image.qcow2 ...

I get this output in stderr 

qemu-system-x86_64 -drive format=qcow,file=image.qcow2 ...: Unsupported qcow version 3

image.qcow2 is a qcow2 image created by qemu-img. error states that problem is with lack support with qcow3 format but real problem is that foramt=qcow is wrong option.

Fix has been included here:
https://git.qemu.org/?p=qemu.git;a=commitdiff;h=197bfa7da7c8eeb39aa5