Vault Error, Server gave HTTP response to HTTPS client

I fixed the problem. Though the exception can be common to more than one similar problem, I fixed the problem by exporting the root token generated after running this command :

vault server -dev

The output is like this

...

You may need to set the following environment variable:

    $ export VAULT_ADDR='http://127.0.0.1:8200'

The unseal key and root token are displayed below in case you want to
seal/unseal the Vault or re-authenticate.

Unseal Key: 1+yv+v5mz+aSCK67X6slL3ECxb4UDL8ujWZU/ONBpn0=
Root Token: s.XmpNPoi9sRhYtdKHaQhkHP6x

Development mode should NOT be used in production installations!
...

Then just export these variables by running the following commands :

export VAULT_ADDR='http://127.0.0.1:8200'

export VAULT_TOKEN="s.XmpNPoi9sRhYtdKHaQhkHP6x"

Note: Replace “s.XmpNPoi9sRhYtdKHaQhkHP6x” with your token received as output from the above command.

Then run the following command to check the status :

vault status

Again, the error message can be similar for many different problems.