Updating my system gives me an unexpected error with vlc

Not sure if this is related because I have been having problems with trying to use X11 but am now back with Plasma (Wayland) and may have borked my system. What is going on here please:-

alastair@HP-Z640-1:~> sudo zypper dup
[sudo] password for root: 
Refreshing service 'openSUSE'.
Loading repository data...
Reading installed packages...
Warning: You are about to do a distribution upgrade with all enabled repositories. Make sure these repositories are compatible before you continue. See 'man zypper' for more information about this command.
Computing distribution upgrade...

The following 8 packages are going to be upgraded:
  libvlc5 libvlccore9 vlc vlc-codec-gstreamer vlc-lang vlc-noX vlc-qt vlc-vdpau

8 packages to upgrade.
Overall download size: 0 B. Already cached: 11.5 MiB. No additional space will be used or freed after the operation.
Continue? [y/n/v/...? shows all options] (y): y
In cache libvlccore9-3.0.18-1699.12.pm.9.x86_64.rpm                                                                     (1/8), 469.1 KiB    
In cache libvlc5-3.0.18-1699.12.pm.9.x86_64.rpm                                                                         (2/8),  82.4 KiB    
In cache vlc-noX-3.0.18-1699.12.pm.9.x86_64.rpm                                                                         (3/8),   3.7 MiB    
In cache vlc-lang-3.0.18-1699.12.pm.9.noarch.rpm                                                                        (4/8),   5.4 MiB    
In cache vlc-qt-3.0.18-1699.12.pm.9.x86_64.rpm                                                                          (5/8),   1.1 MiB    
In cache vlc-codec-gstreamer-3.0.18-1699.12.pm.9.x86_64.rpm                                                             (6/8),  42.1 KiB    
In cache vlc-3.0.18-1699.12.pm.9.x86_64.rpm                                                                             (7/8), 679.6 KiB    
In cache vlc-vdpau-3.0.18-1699.12.pm.9.x86_64.rpm                                                                       (8/8),  58.6 KiB    

Checking for file conflicts: .........................................................................................................[done]
error: can't create transaction lock on /usr/lib/sysimage/rpm/.rpm.lock (Read-only file system)
(1/8) Installing: libvlccore9-3.0.18-1699.12.pm.9.x86_64 ............................................................................[error]
Installation of libvlccore9-3.0.18-1699.12.pm.9.x86_64 failed:
Error: Subprocess failed. Error: RPM failed: Command exited with status 1.
Abort, retry, ignore? [a/r/i] (a): 

It seems you rolled back your system to a read-only snapshot.

Many thanks, I had forgotten all the details as I have never used them before in anger.

Thanks to your putting me right. I have re-traced my original experiment and from the init 3 console I was able undo my error so I do not need the snapshot any more. I do need to re-read all the details from your thread as next time I may need to rely on the snapshot. So, many thanks once more.