Drivers will still have to wait until June for the Wilby Way improvements to end despite an earlier date being published by the Highways Agency.
The scheme, which is part of the Government’s £317 million pinch point improvement programme to boost local economies, reduce congestion and improve safety, got under way at the start of September.
It was said the work to widen and make improvements to the A45 junction in Wellingborough would take about 21 weeks.
But the Highways Agency revealed earlier this month that the scheme may not be finished until June due to the recent wet weather and relocation of a high voltage electricity cable.
This date was then superseded by a new completion date of April 20 published on the Highways Agency website last week.
But after the Telegraph contacted them for a comment, a spokesman said it was a mistake and the website was being changed accordingly.
The Highways Agency spokesman said: “It is an error.
“We are still working towards June for the end of the Wilby Way project, but obviously we will try and make progress as quickly as we can, especially if the weather picks up.”
News of the completion date being brought forward was welcomed by Telegraph readers when the story appeared on www.northantstelegraph.co.uk last week.
But the error means drivers will still have to wait up to four months for the work, which involves widening the A45 eastbound entry and exit at Wilby Way roundabout and the A509 entry and exit, to end.
The estimated cost of the work is £3.5 million and will result in new lanes and traffic signals to assist traffic flow through the junction.
There will also be some associated drainage, tree clearance and street lighting works.
Earlier this month, a spokesman for the Highways Agency said they were doing everything they could to complete the A45 Wilby Way pinch point scheme as soon as possible.
But workers had been severely hampered by the weather and huge amounts of rain.
There was also an issue with a high voltage electricity cable, which needed to be relocated and involved discussions with the supplier Western Power.
The pinch point improvement programme for the strategic road network in England is part of the Government’s growth initiative and aims to provide small improvements which can make a big difference by easing congestion and making journey times more reliable for drivers.