The Illinois Tollway said its online payment system for invoices was "unavailable" Friday.
In a statement, a spokesperson for the tollway said that while all other online services remained available, the option to pay invoices was not working.
The tollway advised customers who want to pay an invoice to call the customer service call center at 1-800-UC-IPASS (800 824-7277).
"The payment due date on invoices will be automatically extended by the duration of the issue for customers who prefer to pay online," the spokesperson said in a statement to NBC 5.
Residents are still able to access their I-PASS accounts and manage them online and pay unpaid tolls via the Pay by Plate Service, the tollway said.