The owner of Frankie & Benny's posted a substantial loss as the group counts the cost of launching overpriced and poorly tested menus.
The Restaurant Group, which owns 488 UK outlets including Garfunkel's and Chiquito, swung to an annual loss of £39.5m in the 53 weeks to 1 January, compared to a pre-tax profit of £86.8m a year ago.
It added that like-for-like sales fell 3.9% over the period, which led to the business to axe 33 sites last summer in response to what it called "a challenging year".
The business said there was "much work to do" to correct the mistakes made in 2016.
The group admitted it had failed to properly test new, more expensive menus with customers, which meant crowd-pleaser dishes like chicken parmigiana had been mistakenly removed at Frankie & Benny's.
The business faces tough competition in the casual dining market from rivals such as Nando's, Byron and Turtle Bay.
Former Paddy Power boss Andy McCue was brought into replace former chief executive Danny Breithaupt in September.
The group said it had slowed down the roll out of its restaurants and would instead focus to "re-establish the competitiveness" of its top brands.
McCue said: "Having completed the strategic reviews of our brands, we are now pursuing a new and focused plan to turnaround and grow the business.
"It will take time to effect the scale of change required and for customers to respond."
Chairman Debbie Hewitt called last year "a challenging year for the group with a consistently disappointing trading performance".
The group said it made an adjusted pre-tax profit of £77.1m, down 11.2%, if it stripped out £116.7m of charges, including the cost of site closures and exiting onerous leases.