The bad blood between Mayor Bill de Blasio and his predecessor is flaring up again, this time over the massive overall of the city’s 911 system, which a new report finds was badly mismanaged by the Bloomberg administration. NY1’s Bobby Cuza filed the following report.

“This was a massive technology project that was mishandled in a number of different respects,” said Department of Investigation Commissioner Mark Peters.

The project was the modernization of the city’s 911 system. Conceived in 2004 under Mayor Michael Bloomberg, the project’s budget ballooned from $1.3 billion dollars to more than $2 billion and its completion date was pushed from 2007 to 2017.

 “Ten years late, $700 million over budget, and a system that still is not working,” said Peters.

Now the city’s Department of Investigation has issued a scathing report, seven months in the making, that faults the project for “persistent mismanagement between 2004 and 2013.”

Mayor Bill de Blasio has of course been critical of many Bloomberg policies; and his Investigations Commissioner is a longtime friend and former campaign treasurer.

But while Mark Peters says the report is not about assigning blame, Bloomberg administration officials are hitting back.

Former Deputy Mayor Cas Holloway issued his own report defending the project,writing, “By the standard that matters most, the 911 overhaul was an overwhelming success: it works. It is faster, has more capacity, new back-up infrastructure, and is more stable and reliable than ever before.”

Holloway even disputes the characterization of the project as over-budget. The only budget increase, he says, took place in 2008, when a decision was made to build a backup 9-1-1 center from scratch in the Bronx.

“Clearly that was a big part of the cost overrun, but it was by no means all of it,” said Peters.

Peters’ report points to numerous problems, from a lack of effective governance to poor recordkeeping.

Holloway says issues were addressed, noting that when Verizon failed to deliver on critical software, causing a three-year-delay, the city won $50 million in damages.

According to the report, the de Blasio administration is already taking steps to implement many of its recommendations, like having a program manager lead all large-scale technology projects, and having a so-called independent integrity monitor, which the city is now in the process of hiring.