Vulnerable people are playing "Russian roulette" when they need care in England, campaigners warn, as a quarter of services are failing on safety.
The Care Quality Commission said drug errors, lack of staff and falls were major problems, after inspecting 24,000 services.
Nursing homes had the worst problems, with a third falling short on safety.
The CQC said the failings across services for the elderly and disabled were "completely unacceptable".
The findings mark the completion of the first round of inspections under the "tougher" system launched in 2014 amid concerns problems were going undetected.
One million vulnerable people use care services - either getting their fees paid by councils or funding it themselves.
More than 200,000 of them live in nursing homes, which had the most serious problems.
Some 37% of homes failed on safety, with inspectors noting they had a particular problems recruiting and retaining nurses.
Just below a quarter of care homes and home helps were rated not safe enough, while in community support, including sheltered housing, 17% fell short.
The CQC highlighted poor care inspectors had found, including:
- the death of a 62-year-old man who had broken his neck in a fall from a shower chair at a West Yorkshire care home. The company in charge of the site, St Anne's Community Services, was prosecuted and fined £190,000
- a number of cases where residents had been put back to bed in the morning because there had not been enough staff to provide them with support
- a 79-year-old woman left with serious burns after falling against an uncovered radiator at Manor Residential Home in London
- cases where incontinence pads had not been changed regularly and were even reused in some instances
- a resident of a home who had died after errors with his anti-blood clotting drugs
- a home that had managed its rotas so badly that care staff had had to help out in the kitchen at lunchtime when residents had needed help
- a home care service in Lincolnshire, Aamina, that had missed calls or carried out rushed visits, with examples of 30-minute calls being done in five
Overall, inspectors have successfully prosecuted five care providers and another 1,000 have had enforcement action taken against them, from being closed down to handed warning notices.
All the services deemed to be failing would continue to be monitored and re-inspected, the CQC said.
But it pointed out that, despite the concerns, most had achieved good or outstanding ratings on safety.
How to pick a good care home
Age UK advises families to check:
- the latest CQC report on the home
- whether the staff are friendly and welcoming
- if senior staff are on duty at all times and whether they know residents and families personally
- whether residents can choose their daily routines
- the ratio of staff to residents and the turnover of staff
- the dementia support available
To find out more, view the checklist here.
Chief inspector Andrea Sutcliffe said funding remained an issue for the sector and a "long-term solution" needed to be found but lack of money was "no excuse".
"There is still too much poor care, some providers are failing to improve, and there is even some deterioration," she said.
"This is completely and utterly unacceptable."
Caroline Abrahams, of Age UK, said the findings were "alarming" and vulnerable people were "effectively playing Russian roulette when they need care".
She added: "Taken as a whole, this report is a graphic demonstration of why older people desperately need the government to follow through on its commitment to consult on proposals for strengthening social care later this year."
Margaret Willcox, president of the Association of Directors of Adult Social Services, said councils and providers would be "re-doubling our mutual efforts to ensure older and disabled people and their families get the reliable, personal care they need and deserve".
Health Minister Jackie Doyle-Price agreed the lapses were "unacceptable".
She said the additional investment announced - £2bn over three years - and the forthcoming consultation on the social care system expected later this year would put the sector on a "stable footing".