The MBTA recently finished installing new fare vending machines on the Orange Line, a milestone in the agency’s ongoing work to make boarding across the transit system “easier and more convenient.”

The new machines will make CharlieCards — as well as new tappable CharlieTickets — available at all subway stations and allow riders to use a smartphone or contactless credit card to pay.

However, not all are finding them so easy.

This fall, MBTA employees — as well as the agency’s Twitter account — have fielded numerous complaints from riders at Orange Line stations about the new machines not processing their credit cards.

The problems, they said, appeared to be exclusive to the new machines, rather than their cards. And even if the old machines’ touch screens can prove finicky at times, riders said that those ones at least took their cards.

Hey @MBTA your new fancy card machines are really bad at reading credit cards. The other week at Haymarket, today at Forest Hills. And I know the card isn't the problem cause I just bought breakfast in the station. Please take a look, I love the idea of these machines!

Today @MBTA, I tried on different new machines at North Station, with my debit and credit card, to reload my CharlieCard and I got the same message: Your bank card is not authorized. You should check these machines. The lines were getting longer and longer!

@MBTA Your new machines don't work at North Station. It won't take either of my cards, and they work perfectly. The old machines did work. What's going on?

@MBTA the newer card machines at State Street were acting up this morning. 1 was down and the other two didn’t want to take my cc. Went over to Govt Center and didn’t have any issue with the older machines.

@MBTA just a heads up tried all 3 new machines at state and none would take my card. Machine at airport worked with no problems

According to the MBTA, the issues seem to stem from new security upgrades included in the new vending machines, which are designed to read credit and debit cards embedded with a microchip, as opposed to the magnetic stripe cards that are slowly being phased out of use by major payment companies.

But for both types of cards, the process is different.

For the majority of users who use chip cards, the new machines require individuals to leave their card in the reader until the transaction has been completed and the screen tells them to “remove card” — unlike the old machines, which had all card users quickly swipe them in and out of the reader.

The vending machines also still accept magnetic stripe cards.

But those users — along with those with cards with broken chips — will be additionally asked to enter their billing address zip code after swiping their card (in the same reader). The MBTA notes that the extra security step is very similar to what is already in place at many gas station pumps and other unattended card terminals.

MBTA spokesman Joe Pesaturo says the agency “is certain that customers will be very satisfied with the new machines,” but says they know the new security features may take time to get used to.

“After 15 years of using the old machines, a learning curve is not unusual,” Pesaturo said, adding that the MBTA plans to include information on their website to “explain the differences in using a chip card and a magstripe card.”

There’s also a separate but related issue that the MBTA is working to fix.

Officials say that if a debit card is used, but a customer chooses the “credit” option, rather than treating the card like a credit card as most systems do, the machine will go on to ask for a PIN number, but the transaction will be denied. The MBTA is working with their vendor to address the issue, the agency said.

Additionally, Visa and MasterCard have their own rules for greater security that, if not followed, could lead to transactions being denied.

MBTA officials note that the fastest way to process an option is to use the machines’ new contactless rectangular tap target. The new machines also no longer dispense the old CharlieTickets that are inserted into fare gates; instead, riders will tap the new paper CharlieTickets at the gates just like a CharlieCard.

We're making it easier for riders to buy fares/passes. Our new upgraded fare vending machines: • Dispense CharlieCards • Print tappable CharlieTickets • Accept mobile + contactless pay Now available at all Orange Line stations with the Blue Line next.https://t.co/vGlkjl5xxP pic.twitter.com/eDxsWEnZ5n

After installing the new machines at all Orange Line stations, the MBTA says it’s began work to do the same on the Blue Line last wee.

The agency is aiming to have all Red, Green, Blue, Orange, and Silver Line stop vending machines upgraded this spring.

Correction: A previous version of this article incorrectly stated that riders could pay with a smartphone or credit card using the circular tap target; that reader is only for CharlieCards or the new tappable CharlieTickets. The smaller rectangular target is for paying via phone or card.

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