Unable to start start fleet server

Hi,
I am trying to start fleet server. However, I encounter the following error when starting it:

Fleet Server - Error - info fail [401 Unauthorized] {"error":{"root_cause":[{"type":"security_exception","reason":"failed to authenticate service account [elastic/fleet-server] with token name [fleet]","header":{"WWW-Authenticate":["Basic realm="security" charset="UTF-8"","Bearer realm="security"","ApiKey"]}}],"type":"security_exception","reason":"failed to authenticate service account [elastic/fleet-server] with token name [fleet]","header":{"WWW-Authenticate":["Basic realm="security" charset="UTF-8"","Bearer realm="security"","ApiKey"]}},"status":401}

Any idea how to solve it?

I think you need to share more details about what have you done. Did you enroll the agent? Did you update it? Did you try to regenerate the API key?