Charlotte Rae Died of Cardiac Arrest According to Death Certificate

Charlotte Rae died after going into cardiac arrest ... and she was also battling salivary gland cancer ... TMZ has learned.

According to the "Diff'rent Strokes" and 'Facts of Life' star's death certificate, Rae's immediate cause of death is listed as cardiopulmonary arrest, while metabolic acidosis -- an abnormal acid buildup -- and carcinoma of the right parotid gland were contributing factors.

In line with her announcement she had been diagnosed with bone cancer last year, the death certificate, obtained by TMZ, does not include any other significant conditions.

As we reported ... Rae passed away last Sunday in her L.A.-area home. She played the beloved character Mrs. Garrett on "Diff'rent Strokes" before starring in the spin-off, "The Facts of Life."

Charlotte was 92. RIP