Erin Moran died from complications of advanced cancer.

The 'Happy Days' actress passed away at the age of 56 last month, and despite struggling with addiction issues for several years, a coroner's report into her passing confirmed ''no illegal narcotics were involved in her death'', TMZ reports.

Erin's husband, Steven Fleischmann, previously spoke about his wife's rapid decline but admitted even he had no idea how mad things were until after her death.

In an open letter, he wrote: ''It got so bad so fast. By the middle of February, Erin could no longer speak or eat or drink. She had a feeding tube implant and i feed her 6 to 8 times a day. She was still happy, she was active, she texted people on her phone all day. On the 21st she was having trouble breathing. She woke up on the 22nd, she was not 100%. She needed Kleenex, so i went to the store and came back. She was there watching T.V in bed.

''I laid down next to her held her right hand in my left. I feel asleep woke up about a hour later still holding her hand and she was gone, she was just gone.. Norton Cancer Institute never said how bad it was.. The coroner told me it was really really bad. It had spread to her spleen, she had alot of fluid in her lungs and part of her brain was infected. The coroner said even if she was in the hospital being pumped full of antibiotics she still would not of made it. He said it was the best that she was with me and went in her sleep (sic).''