Sometimes when you update or install any application in Ubuntu you will get a opera based error. This will happen because of the opera update problem. You can solve this easily via the below method. Complete error will look like below in your terminal.
dpkg: error processing package opera-stable (–configure):
installed opera-stable package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
E: Sub-process /usr/bin/dpkg returned an error code (1)