Computer specialists are working to fix security holes that have halted work on a database to protect children.
The £224m ContactPoint database contains the name, address, gender, date of birth and a unique identifying number for all people aged under 18 in England, together with details of their parents, school and doctors' surgery.
Work updating the database of 11 million children was stopped after the details of vulnerable children were accidently exposed.
Concerns were raised by some of the 300 workers at local authorities in England who are shielding details on the system before it goes live.
ContactPoint's shielding system was supposed to remove all details of the estimated 55,000 vulnerable children — apart from the name, sex and age — from the database, which will be available to children's services workers across the country.
However, a flaw in the system meant when certain records were updated, a duplicate was created where the details were not shielded.
Shadow children's minister, Tim Loughton, said in a statement: "ContactPoint is not even live and it is coming apart at the seams. The government should have foreseen these issues five years ago when they first drew up plans for this expensive and unnecessary database.
"The government has proved that it cannot be trusted to set up large databases or to keep our data secure. Despite these serious and widespread concerns, ministers seem determined to bulldoze ContactPoint through."
The Department for Children, Schools and Families has now halted work on updating details on ContactPoint until the flaw has been fixed.
A spokeswoman for the department said that the problem will not delay plans for the system to go live this year.
She said: "Our colleagues have been working very quickly with local authority representatives to put the problems right. Fifty-percent of problems flagged up have already been identified as human error."
She said the unshielded details had only been exposed to the 300 local authority workers who were updating the system, all of whom had been vetted and cleared to access the children's information.