What does it mean when you dream about an old friend already dead?

Answer 1

To dream of seeing the dead, living and happy, signifies you are letting wrong influences into your life,

which will bring material loss if not corrected by the assumption of your own will force.

To dream that you are conversing with a dead relative, and that relative endeavors to extract a promise from

you, warns you of coming distress, unless you follow the advice given you. Disastrous consequences could

often be averted if minds could grasp the inner workings and sight of the higher or spiritual self. The voice of

relatives is only that higher self taking form to approach more distinctly the mind that lives near the material

plane. There is so little congeniality between common or material natures that persons should depend upon

their own subjectivity for true contentment and pleasure.

Would add this to the above. It could mean that in your subconscious mind there are memories of the dead person whom you like or dislike intensely. There could be unsettled issues with the dead person . Subconscious mind is so power full it can bring in the form of dreams, solutions to problems. There are real cases of Scientist getting solutions in the dream for their daylight problems.

A different perspective:

There is no single meaning that can be applied to all dreams about a deceased person. The dreamer's subconscious mind, also called the soul, sometimes uses the image of a dead person to represent some event or memory from the dreamer's past. It is necessary to consider other details from the dream, such as the location or actions in the dream, to comprehend its message.

It is also entirely possible that something encountered in waking life, whether noticed consciously or not, could have triggered the image of the dead person in the dream.

Exactly. This is more close to the issue.
you feel guilty