After more than a week of confounding problems with getting newspapers to subscribers, The Boston Globe has turned to its former distribution partner to handle about half of its home deliveries across the region, chief executive Mike Sheehan said Tuesday.

The deal, with Publishers Circulation Fulfillment Inc., followed an unexpectedly difficult rollout for the Globe’s new vendor, ACI Media Group, which left tens of thousands of newspapers undelivered in its first week after taking over distribution in the Boston region on Dec. 28.

Sheehan predicted “an extremely rapid return to 100 percent deliveries and improved customer service’’ after PCF starts operating its routes on Monday. The company also may help with delivery of this Sunday’s paper.

“We can’t apologize too much’’ to readers, Sheehan said, moments after the deal was consummated.

Maryland-based PCF has agreed to resume deliveries throughout a swath of territory defined roughly as extending from the Cape Cod Canal to Boston and west to Wellesley and Weston, as well as territory north of Boston from Peabody to Newburyport and east to Rockport.

Its turf includes about 50 percent of the home delivery customers in the Greater Boston market, Sheehan said.

Financial terms of the deal were not disclosed.

The Globe is seeking to end a customer relations nightmare that marked the most substantial business misstep under owner John W. Henry, who bought the paper in 2013. Henry apologized to readers in a letter published Wednesday in the Globe opinion pages.

The breakdown of home delivery triggered overwhelming frustration and anger. Readers calls flooded the paper with complaints that so overwhelmed the telephone system that it was often impossible for calls to get through. It was also difficult for reporters to place calls out from the newsroom.

The paper has recorded about 2,000 subscription cancellations since the problems began, according to Globe officials, more than 30 percent higher than the typical rate.

Under the new arrangement, ACI will, ideally, devote its delivery resources to fewer subscribers in more confined geographic areas, in places they’ve avoided significant problems, Sheehan said. “This simplifies things for them and will allow them to be successful,’’ he said. The distribution areas shifting to PCF are ones where ACI experienced the most trouble making its deliveries, Globe officials said.

The move comes after two days of negotiations with the companies, during which ACI agreed to take the reduced role, Sheehan said.

“These were not at all contentious negotiations,’’ Sheehan said of the talks with ACI, a Long Beach, Calif., company

In a statement, ACI president Jack Klunder said, “We understand how important The Boston Globe is to its subscribers and the community at large, and this will help restore delivery dependability as quickly as possible.’’ Klunder apologized for “disappointing some readers as we entered the market.’’

PCF could not be reached for comment.

ACI officials acknowledged in interviews on Sunday that after a week on the job, they did not have enough drivers to cover all routes. The company said it was aggressively trying to hire more, but faulted the Globe for not properly warning readers about disruptions that would come with the switch.

Globe officials responded at the time that ACI had never warned that thousands of subscribers would go unserved.

The Globe has about 115,000 daily subscribers and 205,000 on Sunday. About 90,000 daily and 190,000 Sunday subscribers live within the territory that ACI took over last month. ACI had acknowledged that up to 10 percent of papers were not delivered on its worst day.

Globe officials have said the move to ACI was intended to improve service and reduce cancellations, as well as to save money. The new arrangement will still provide some cost savings, but less than the company had originally anticipated, Sheehan said.

Company officials said the volume of calls to the Globe’s customer service center declined significantly Tuesday. Subscribers who failed to get through but whose phone numbers were logged by the Globe’s system will automatically receive a credit on their bill, executives said.

Meanwhile, other Boston-area publications that contract with PCF warned their subscribers of delivery problems. The Boston Herald, MetroWest Daily News, and Lynn Daily Item all acknowledged delayed or missed deliveries, and readers complained that delivery of The Wall Street Journal and The New York Times was affected in some areas.

In a statement, the Herald said, “The Globe’s decision to change delivery vendors has impacted the distribution of all newspapers in our market, and as a result we are experiencing some late deliveries.’’

The Daily Item blamed its problems on “a ripple effect resulting from another newspaper’s change in distribution vendors.’’

The notice quoted a PCF executive as saying that the decision of a client to use another distribution company had forced PCF to restructure its delivery routes. PCF has also lost drivers to ACI’s hiring push.

Sheehan said that Globe executives turned to PCF “to get newspapers back into the hands of our readers as quickly as possible.’’

Asked what the newspaper has learned from the disastrous past 10 days, Sheehan gave a rueful smile and said, “Where do you want me to start? My God.’’

“It is extremely difficult to do something like this without a transition period,’’ he offered. “To flip a switch overnight is more disruptive than anyone would have ever imagined.’’

“And more important,’’ he said, “for a company that’s about to invest a lot of money in a print production facility in Taunton, it’s a reaffirmation of how important the print product is and is going to be for a long time.’’

“We learned how many people in this market for whom the [printed] Globe is their link to the outside world.’’

And, he said, the paper learned, “Never let down the customers again.’’

Mark Arsenault can be reached at mark.arsenault@globe.com. Follow him on Twitter @bostonglobemark. Adams can be reached at dadams@globe.com. Follow him on Twitter @DanielAdams86.