The escalation of a fire that ripped through an 18th Century hotel caught "relaxed" firefighters by surprise, an independent report has found.
Exeter's Royal Clarence Hotel, described as England's oldest, was reduced to a shell in October 2016.
The National Fire Chiefs Council (NFCC) report said there was a "relaxed feeling" before the fire escalated.
Devon and Somerset Fire and Rescue Service said "valuable points" had been made in the report.
The fire service released its own report shortly after the fire, but a former fire officer accused bosses of "covering up" a missed opportunity to save the hotel. Sector commander Dave Jones said the overall command team ignored advice to send crews back inside at a crucial time.
Evidence obtained by the BBC in November 2018 revealed that, after it was discovered the fire had spread to the third floor of the hotel, advice to deploy crews inside was not followed.
The NFCC report said: "The escalation of the fire in the Royal Clarence Hotel caught everybody by surprise and was unexpected.
"This escalation was a significant development at this incident and changed the 'battle rhythm' on the fire ground from one that was described as being 'relaxed'," it added.
Firefighters were said to have been expecting to move into the "recovery phase" of the operation.
Crews tackled the fire from outside until the blaze broke through the hotel roof. Firefighters were then sent inside.
The report also said that "detectable fire spread" was not monitored because of the "absence of a continual watching brief" after the decision had been taken to fight the blaze from outside the building.
The fire service said: "We care deeply about the safety of our firefighters and will not put them at unnecessary risk, particularly when there are no lives to be saved."