I have a simple solution that so far has worked perfectly. I uninstalled Opera 78.0.4093.147 and downloaded and installed version 77.0.4054.277 from the Opera website . This is the last version of Opera in which the sidebar worked properly. I did a little bit of surgery on the installation to keep Opera from auto-updating, and so far it is hanging in there. I check the Opera website periodically to see if they have an update. So far - nothing. .