On Wednesday, October 30, 2013 10:14:19 PM UTC, wrote:
Recently my Freedom Pass has failed at some Oyster Readers (usually Underground ones)with an error 94.



The only thing that has changed is that I now have in my wallet a proximity debit card.



Would this cause problems?

In my experience even a first generation chip and pin card could interfere with any variant of an Oyster card being read. I always carried mine in a separate wallet and now use a third wallet for my ENCTS card.