If you were flying Delta on Sunday, January 29th, chances are your flight was affected by their computer outage.

Over 150 flights were either delayed or cancelled a result of the computer outage. A ground stop was put in place for all of Delta’s domestic flights in the U.S. on Sunday evening, according to the Federal Aviation Administration (FAA) in an announcement.

The outage occurred at around 6:30 p.m. It took crews a few hours to get the computers working again. In a statement on Monday, January 30th, Delta said that the systems were working as they should sometime after 12:00 a.m.

Despite the computer errors being fixed, Delta said that about 110 flights were cancelled on Monday. The airliner said that more cancellations are not unlikely.

Delta CEO Ed Bastian issued the following apology to Delta customers early on Monday, “I want to apologize to all of our customers who have been impacted by this frustrating situation… This type of disruption is not acceptable to the Delta family, which prides itself on reliability and customer service. I also want to thank our employees who are working tirelessly to accommodate our customers.”

According to Delta, the outage did not impact flights that were in progress. Delta did say there were some delays upon landing. The ground stop did not affect international flights, according to the FAA. However, some Twitter users said their foreign-bound flights were affected.

The Delta outage came after President Donald Trump inked an executive order on immigration on Friday, January 27th. The executive order puts a 90 day limit on immigration from seven countries which are majority Muslim. In addition, refugees are barred from entering the U.S. for a period of 120 days. Syrian refugees are also not allowed to enter the U.S. for an undetermined period of time.

People protested President Trump’s executive order at some U.S. airports. Trump tweeted the following two-part tweet in response to the protests and the Delta outage, “Only 109 people out of 325,000 were detained and held for questioning. Big problems at airports were caused by Delta computer outage,….. protesters and the tears of Senator Schumer. Secretary Kelly said that all is going well with very few problems. MAKE AMERICA SAFE AGAIN!”

Delta issued its own statement to customers after Trump signed the executive order. Their statement was posted on January 28th, and it reads in part, “Delta will make every effort to contact impacted customers with flexible rebooking options including refunds.”

This is not the first time Delta has experienced issues with its computer systems. An estimated 2,000 flights were cancelled in August after a power outage at Delta’s Atlanta operations center. The flight cancellations lasted for a few days. Delta said it would issue refunds and travel vouchers to customers who were affected by the August outage.

Delta is also not the only airline to experience a computer outage in recent days. On Sunday, January 22nd, every domestic United Airlines flight had to be grounded due to a computer outage.