System: 64-bit Linux Mint ver: 17.3 fully up to date as of 20/01 - 100+Gb free disc space - 8 Gb memory. Opera ver: 42.0.2393.137 for 64-bit Linux.
In view of the increase in web fraud, large retailers are increasingly making use of the "Verisign" system. Under this the final steps of the checkout/payment operation is to redirect to the "Verisign" organisation. The user has previously arranged matters with their Bank --  That a secret welcoming phrase will be presented to the user by Verisign, thus confirming that they are indeed in contact with the verifying organisation.  The user must input three random characters from a previously-agreed password. This step confirms to the vendor that the person is genuine.
The problem is that Opera blocks this connection so the transaction cannot be verified and the whole purchase operation fails. Having spent an hour or so creating a list of (say) a month's worth of groceries, it is very frustrating to have the transaction aborted at the very last minute due to a quirk in the browser. I normally run Opera sandboxed, using the "firejail" utility and with several Add-ons (No-Script Lite, uBlock, Fast Image Blocker, HTTPS Everywhere, Privacy Badger) plus the in-built Ad-blocker all activated and this configuration is compatible with all the sites I visit except Verisign. However, I have tried running Opera with all Add-ons disabled but still get the same error message -- "arcot blocked" where the URL of Verisign is "secure5.arcot.com".
Interestingly, Firefox, vers 50.1.0 does not apparently have any such difficulty in contacting to the verifying site. Although I have long used Firefox, I have recently changed over to using Opera a my default browser because of its clean UI and its speed. I do not want to use a second browser just to shop at Sainsbury's but this seems to be my only alternative.
Has anyone got any suggestions or a work-around for this problem ?
Best regards to all ---