The RHI Inquiry Report has found no evidence of corruption but criticised the behaviour of some ministers and special advisers as "wholly inappropriate".
Sir Patrick Coghlin's report into the cash-for-ash scandal, which brought down the last power-sharing Executive, was released at 2pm on Friday.
The public inquiry was set up after the costs of the green energy scheme spiraled out of control because of generous subsidies.
Sir Patrick's report comprises three volumes, 656 pages, 56 chapters, 276,000 words, 319 findings and 44 recommendations.
The inquiry found that Dr Andrew Crawford, who was DUP leader Arlene Foster's special adviser when the scandal broke, did not "deliberately delay" the introduction of cost controls.
However, the report criticises Dr Crawford for passing on confidential information about the introduction of cost controls in the summer of 2015. He did so before then DETI Minister Jonathan Bell had even approved the cost control measures. The inquiry heard evidence that Dr Crawford had passed on the information to family members.
"The Inquiry finds it totally unacceptable that Dr Crawford provided confidential information to external parties, including his family," the report states.
The extent of information passed on to some market participants, including chicken producer Moy Park, by officials was "wholly inappropriate", the report adds.
The inquiry heard that then DETI Minister Arlene Foster did not read the RHI regulations before recommending the scheme to be opened in 2012.
"The inquiry considers that the Minister (Foster), in presenting the regulations to the Assembly and asking for their approval, should have read them herself, not least because, in the Inquiry's view, to do so is a core part of a Minister's job."
The report does state that if Mrs Foster and her special adviser Dr Crawford had read the regulations "it may not have made any difference to the outcome" of the scheme.
Dr Crawford, in his role as special adviser to the then finance minister, did not pass on to Minister Foster his market intelligence about gaming or about a "massive spike in applications," the inquiry found.
"The Inquiry finds this unacceptable considering the potential financial impacts that would very clearly be of interest to Ms Foster as Finance Minister."
The inquiry considers that the Minister (Foster), in presenting the regulations to the Assembly and asking for their approval, should have read them herself, not least because, in the Inquiry's view, to do so is a core part of a Minister's jobRHI Inquiry report
The inquiry also found that DETI officials did not correctly explain the funding position to Minister Foster, or Dr Crawford, during their time in the department.
It says it is clear that up to at least July 20, 2015 Dr Crawford, then Finance Minister Foster's special adviser, still wrongly believed that RHI funding was coming from the UK Treasury with "no potential impact on NI budget".
This was incorrect.
The inquiry found that whistleblower businesswoman Janette O'Hagan was an "impressive witness".
O'Hagan first raised concerns with DETI officials in 2013 about the incentive for boiler owners to "burn-to-earn".
She met with DETI officials in October 2018 but her concerns were not acted upon.
"It was not difficult to sympathise with her sense of frustration at the apparent inaction of a government department for some two years, even failing to carry out any investigation into the evidence that she had provided", the report reads.
The report adds: "Ms O'Hagan deserved better and had every right to feel aggrieved particularly when, in December 2016, her email of 26 August 2013 was released in an inadequately redacted form, contrary to her clear instruction and her request that her identify be protected."
The inquiry found that DUP special adviser Timothy Johnston, who denied trying to delay the introduction of cost controls, was "much more involved in the RHI scheme discussions, including tariff controls, than Mr Johnston's evidence to the Inquiry would suggest".
DUP special adviser Timothy Cairns, who worked with DETI Minister Jonathan Bell when the scandal broke, told the inquiry that Mr Johnston had said to delay cost controls.
"Inquiry considers that the contemporaneous email evidence was consistent with and supports evidence of Mr Cairns that Mr Johnston had made a statement about not introducing tariff controls," the report states.
The inquiry found that a "high degree of rapport and trust" contemplated by the code of conduct between Mr Cairns and Mr Bell "did not exist".
The report notes the break down in trust between the pair "made resolution of the RHI problems more difficult".
The inquiry also found that there was a significant lack of effective leadership within DETI in the early weeks of June 2015.
The report criticises former Stormont Minister Simon Hamilton whose special adviser leaked emails from civil servants in January 2017 to the media. With Mr Hamilton's consent, John Robinson sent an envelope containing copies of the emails to journalists.
The emails from the summer of 2015 detailed contact between officials in the Department of Enterprise, Trade and Investment (DETI) and those in the energy industry.
The inquiry found the disclosure of emails was intended to "relieve, to some degree", the pressure on one form of civil servant, a special adviser, by making public the identities and actions of more junior civil servants.
"While, in some respects, Mr (John) Robinson, Mr (Richard) Bullick and Dr Crawford were all participants in this action, it was quite extraordinary and unacceptable step for an Executive Minister to also acquiesce."
The report found that "corrupt or malicious activity" on the part of officials, ministers or special advisers was "not the cause of went wrong with the NI RHI scheme.
Rather it was an accumulation of errors, omissions over time and a failure of attention, of those involved.
The report makes a wide range of recommendations for reform of the civil service.
Including new induction processes for special advisers, changes to recruitment process, a revision of the special adviser code of conduct and that a new code of conduct for NI Ministers should be introduced to reflect the findings of the RHI inquiry.