The spectacular best picture mix-up at this year’s Oscars was a humiliating moment for the Academy of Motion Picture Arts and Sciences, the presenters Warren Beatty and Faye Dunaway, and especially the accounting firm PwC — but it will not cost the firm its prized client.

In a letter to academy members on Wednesday, the group’s president, Cheryl Boone Isaacs, said the organization’s board of governors had decided to continue working with PwC despite being, she wrote, “unsparing in our assessment that the mistake made by representatives of the firm was unacceptable.”

But she said that after spending a month reviewing the academy’s deep relationship with PwC — the firm, previously known as PricewaterhouseCoopers, also does the academy’s audits and taxes — the board of governors voted to keep PwC, with new protocols in place that included adding a third “balloting leader” to the Oscars team, instituting rehearsals, banning electronic gadgets and increasing oversight by PwC’s United States chairman.

PwC has tabulated the academy’s Oscar votes more or less seamlessly for the past 83 years, with its Oscars accountants proudly strutting down the red carpet before each ceremony, toting sleek leather briefcases containing the winners’ envelopes. Then came the Feb. 26 ceremony, when “La La Land” was erroneously declared the best picture winner, followed by fleeting jubilation and then confusion and chaos onstage, before, in a shocking and excruciatingly awkward scene, the correct winner, “Moonlight,” was announced.