A £235m government database containing the records of England's 11 million children has been switched off.
ContactPoint was established in the wake of the Victoria Climbie child abuse case to aid child protection.
The report into her death highlighted the need to improve the exchange of information between different agencies working with vulnerable children.
The government argued the system was disproportionate to the problem, so is looking at developing other solutions.
Within two months of the switch-off all the data collected for the system is to be destroyed, although the information will still remain in the social services, education and health departments it had been gathered from.
But there have been concerns that there is nothing collating key information centrally in one place.
The system, which has been running since January last year, was always controversial and was set to cost a further £41m a year.
After successive delays, it was rolled out to only 15,000 users, out of the initial target of 330,000.
The system was used by doctors, social workers, schools, charities and other individuals involved in the protection of children.
Many said it was useful in tracking children and discovering the truth about the way they are cared for.
But civil liberties groups criticised it as intrusive and disproportionate.
'Not the answer'
They were concerned about keeping information on all of England's children in one place and feared that it was not secure.
In July, Children's Minister Tim Loughton confirmed that the government was scrapping the scheme.
He said he recognised the problem that the previous administration was trying to solve when it established ContactPoint.
"Front line practitioners need to be able to provide support for our most vulnerable children when they move across local authority boundaries or access services in more than one area," he said.
"Experience shows the potential value of a quick and reliable means of discovering whether another professional has worked with such a child.
"It is worth considering a national approach to that issue."
However, he was clear that ContactPoint was not the answer.
He told BBC Radio 4's Today Programme: "We need a better child protection system in this country, but at the end of the day it's not a computer system that will save vulnerable children.
"It's the performance of the professionals at the sharp end, who need to be properly trained and resourced."
Instead, he is looking at establishing a new national service which would focus on helping practitioners find out whether another practitioner is working, or has worked, in another authority area with a child.
Decommissioning of the information contained on the database began at noon on Friday.
The shadow children's minister, Delyth Morgan, said the decision to close down the database was "very short-sighted".
"The Government appears to be scrapping ContactPoint without putting any appropriate safeguards in its place and without giving any thought to the consequences," she said.
"Scrapping it now won't save a great deal of money as the investment in set up has already been made and the government has confirmed that they have made no assessment of the social worker and other professionals' staff hours Contactpoint saves, which will now be lost," she added.
Here are a selection of your comments