Passengers holding valid passes have been suddenly finding them not being accepted due to issues with technology.
The council has been working with suppliers to resove this throughout the day but has now said the problem is likely to continue into the weekend and next week.
However, the authority has reassured all pass holders that their passes will still be accepted on bus and tram services.
In a statement on its Facebook page, the council said: “We're still working to resolve the system issue with bus pass acceptance which is stopping some valid county council passes, including concessionary passes, working on bus and tram services.
“It's likely that this issue will continue into the weekend and next week and we'd like to say thank you for your patience whilst we work to resolve this with the supplier.
“If you have a county council pass and are due to be travelling on local bus or tram services, your valid pass will still be accepted for travel when shown to the bus driver or tram conductor.
“We'll keep you updated on this issue as we work hard to resolve it.”