LOS ANGELES — More U.S. homes entered the foreclosure process in October than in the previous month, with Florida, Pennsylvania and Indiana registering among the largest monthly increases, new data show.

Some 77,733 properties received an initial default notice last month, up 10 percent from September, foreclosure listing firm RealtyTrac Inc. said Thursday.

The number of homes scheduled to be auctioned or repossessed by lenders also posted monthly increases.

All told, notices of default, scheduled auctions and bank repossessions — warnings that can eventually lead to a home being lost to foreclosure — hit a seven-month high in October.

The numbers are further evidence foreclosure activity is picking up.

The activity slowed a year ago after problems surfaced with the way many lenders were handling foreclosure documentation, namely shoddy mortgage paperwork comprising several shortcuts known collectively as robo-signing. Many of the nation’s largest banks reacted by temporarily ceasing all foreclosures, re-filing previously filed foreclosure cases and revisiting pending cases to prevent errors.

But banks appear to be moving past those problems now and starting to tackle a swelling backlog of homes with mortgages that have gone unpaid — something that lenders are seeing more of as the economy struggles and unemployment remains high.

The rate that homeowners were 60 or more days late on their mortgage payment rose in the June-to-September period for the first time since the last three months of 2009, according to TransUnion.

The credit reporting agency said 5.88 percent of homeowners missed two or more payments, an early sign of possible foreclosure. That was up from 5.82 percent in the second quarter of 2011.

The number of U.S. homeowners underwater on their mortgage, or owe more than their homes are worth, represent another potential source of trouble for lenders.

As of June 30, some 22.5 percent of all U.S. homes had a mortgage that was under water, according to CoreLogic. That’s 10.9 million properties. Another 2.4 million borrowers had less than 5 percent equity in their home, the firm said.