A previously confidential report on a sea defence contract awarded by Scarborough Council reveals "a sorry tale of errors and complacency".
Faults have already been detected in the sea defences
The Penn report looked at the circumstances surrounding the award of a contract for the sea wall.
The town's former chief executive, John Trebble, retired last month and withdrew a request that the report never be made public.
The report says the contract led to public ridicule for the authority.
The one-metre-high concrete sea wall replaced the original iron railings along Marine Drive in 2005, as part of a two-kilometre scheme designed to protect the resort.
It cost more than £53m - almost £30m more than first expected - but faults have already been detected.
The independent Penn report was commissioned after the Audit Commission found a consultancy contract worth more than £1m had been awarded illegally, as it was not advertised in Europe.
The report's author, Richard Penn, said it pointed to "what is seen both inside and outside the council as a sorry tale of errors, complacency and lack of 'corporateness' on the part of key individuals.
"The result has been a period of embarrassment and even public ridicule for the council at large and for individual elected members.
"None of the key senior council officers involved at that time in this episode come out of it well, but it is difficult to allocate individual responsibility given the problems I experienced in meeting with a number of the key players, including senior officers who have left the council's employment.
"The fact that there is no evidence of financial loss or fraudulent activity, whilst welcome, does not detract from the serious nature of the failure to ensure effective governance of the council's business.
"It is clear and very encouraging that the council appears to have learnt a great deal from this difficult experience and I saw a genuine desire on the part of virtually all those that I spoke to during my investigation to use the experience to help change the culture of the organisation."
Leader of the council Eileen Bosomworth said she hoped the publication of the report would be an end to the matter but insisted that lessons had been learned.
"We have taken up all of the auditor's recommendations and implemented everything to the last word," she said.
"And we will continue to learn lessons."