I found similar error in new installation also. I notice the mismatch error occurs when updating Kernel version 4.15.0-30-generic. Before 4.15.0-30-generic version apt-get update works like charm but afterward it failed for updates universe repository.
I found similar error in new installation also. I notice the mismatch error occurs when updating Kernel version 4.15.0-30-generic. Before 4.15.0-30-generic version apt-get update works like charm but afterward it failed for updates universe repository.