UPDATE: Sony has removed the option to redeem vouchers while it continues its investigation into the PSN disruption.
"We are aware that users are experiencing some disruption to the PSN service," wrote SCEE Blog Manager Fred Dutton on the EU PlayStation Blog. "To minimise the inconvenience we have suspended the 'redeem voucher' functionality whilst we investigate further. Unfortunately this means that money cards, product vouchers, PlayStation Plus vouchers, PS3-PS4 upgrade vouchers and any other vouchers for digital content are not redeemable at this stage. Other PSN features such as log-in, online multi-player gaming, PlayStation Plus trial, PS Store (excluding voucher redemption), trophies, messages, friends etc. are all available."
"We apologise and will provide an update to this announcement soon."
ORIGINAL STORY: Now that the PS4 has finally launched in Europe, users are experiencing problems logging in to PSN - an especially big irritation as several of the console's features aren't available until it receives a day one update.
"We are aware some users are experiencing issues logging into PSN on PS4 due to the heavy traffic we are receiving, we're investigating," noted the PlayStation Europe Twitter feed. "Thanks for your patience."
A Twitter search for "PSN" has yielded throngs of angry fans unable to connect to the online service.
Sony attempted to brace itself for these issues by shutting down some PSN features yesterday, but it looks like this only helped so much. These sorts of login issues are common at launch - and indeed I experienced them when I purchased my PS4 in the US upon its launch two weeks ago - so hopefully these connection issues will get resolved shortly. We'll keep you posted.