Schneider National is blaming a “firmware defect” tied to an external vendor’s equipment for a massive computer network outage that knocked the trucking giant offline on Thursday.

In a statement to FreightWaves on Monday, the company said it is operating normally and “began accepting orders and dispatching our drivers electronically on Saturday.”

On Thursday, Schneider (NYSE: SNDR), headquartered in Green Bay, Wisconsin, was forced to switch to manual operations to book freight, execute loads and pay carriers, citing a “temporary systems issue.”

The company, which has been in business for 87 years, didn’t disclose the name of the external vendor with the firmware defect that caused its entire network to shut down, other than to state that the affected equipment has been replaced, “enabling Schneider to resume normal activity.”