Upload post image fails . Something went wrong :(

Ghost-CLI version: 1.13.1
Ghost version: 3.5.0

When I try to upload post image I get an error that is not very informative: “Something went wrong :-(”
In error.log I see this:
at Function.process_params (/var/www/ghost/versions/3.5.0/node_modules/express/lib/router/index.js:335:12)"},"msg":"Authorization failed","time":"2020-03-26T09:51:25.716Z","v":0}
Where can I troubleshoot this?