Debbie Reynolds died from a blood vessel that ruptured and caused bleeding in her brain ... this according to her death certificate.
According to the doc -- obtained by TMZ -- Debbie's official cause of death was an intracerebral hemorrhage ... essentially a stroke. It also lists hypertension as an underlying cause of the stroke.
Reynolds died in an L.A. hospital Dec. 28, just one day after daughter Carrie Fisher died after a massive heart attack.
TMZ broke the story ... Reynolds was rushed to a hospital when someone from her son Todd's home called 911 to report a possible stroke.
Todd told us his mom was talking about Carrie just before suffering her stroke, and said ... "I miss her so much, I want to be with Carrie."
Reynolds was 84.