The government runs the risk of another Windrush scandal if "serious concerns" about its EU settlement scheme are not addressed, MPs have said.
The Commons Home Affairs Committee said technical issues had "blighted" the scheme, with some struggling to navigate the online application system.
It said people who have lived for years in the UK could face uncertainty over their rights and eligibility to remain.
But the Home Office said the scheme was "performing well".
It had "taken great care to learn from the experience of the Windrush generation", it said, referring to the scandal that saw wrongful detentions and deportations of people living in the UK who arrived from Caribbean countries between 1948 and 1971.
EU citizens in the UK before Brexit can apply for settled status through the scheme, which allows them to continue to live and work here afterwards.
But applicants and campaigning groups have criticised the system, saying it has proved slow and bureaucratic for some.
The committee said it had "serious concerns" that the design of the Home Office's settlement scheme means some EU citizens were at risk of being left out.
It said there was a "lack of clarity" over the scheme and it was "vital" that the Home Office got the detail of the scheme right.
"Failing to do so will run the risk of another Windrush scandal," it said.
"EU citizens - who may have been legally resident in the UK for many years and have made this country their home - could be left in an uncertain situation regarding their rights and eligibility to remain in the UK."
It said these people "should have their rights protected and their entitlement to remain enshrined in law".
Committee chairwoman Yvette Cooper, a Labour MP, said the government's plans for the EU settlement scheme showed it was "not learning the lessons from the scandal".
"The problems faced by the Windrush generation showed how easily individuals can fall through gaps in the system through no fault of their own and how easily lives can be destroyed if the government gets this wrong," she said.
What was the Windrush scandal?
An estimated 500,000 people now living in the UK who arrived between 1948 and 1971 from Caribbean countries have been labelled the Windrush generation, a reference to a ship which brought workers to the UK in 1948.
They were granted indefinite leave to remain in 1971 but thousands were children travelling on their parents' passports, without their own documents.
Changes to immigration law in 2012 meant those without documents were asked for evidence to continue working, access services or even to remain in the UK.
Some were held in detention or removed despite living in the country for decades, resulting in a furious backlash over their treatment.
The scandal prompted criticism of "hostile environment" measures introduced to tackle illegal immigration, now referred to by the government under the heading "compliant environment".
It was followed by the resignation of Home Secretary Amber Rudd.
The Home Office said it disagreed with the committee's assessment of the scheme, which was "performing well with more than 600,000 applications received by the end of April and hundreds of thousands of people already being granted status".
A spokesman said: "The scheme protects the rights of EU citizens in UK law and gives them a secure digital status which, unlike a physical document, cannot be lost, stolen or tampered with."
He said there were 200 "assisted digital locations across the UK to help EU citizens apply" and £9m available for 57 UK organisations to support an estimated 200,000 vulnerable people to apply.
The Home Office has previously said the government was committed to protecting the rights of EU citizens in the UK.
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