This sections enumerates potential connection problems with crash, and how to investigate and resolve them.

Debugging connection errors

If you are connecting to CrateDB, for example like this:

crash --hosts 'http://localhost:4200' -U 'admin' -W

… and crash responds with a connection error message like this:


you may want to add the --verbose command line option, in order to find out about the reason why the connection fails. It could be a DNS / name resolution error, or it could be a problem related to SSL termination.

Other than --verbose, you can also use the shorthand version -v:

crash --hosts 'http://localhost:4200' -U 'admin' -W -v

SSL connection errors

A recent problem outlined SSL connectivity problems when connecting to CrateDB Cloud:

crash --hosts '' -U 'admin' -W -v

The verbose output using crash -v signaled a certificate verification error like that:

Server not available, exception: HTTPSConnectionPool(host='', port=4200):
Max retries exceeded with url: / (Caused by SSLError(SSLCertVerificationError(1, '
[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1006)')))

If you are on macOS, the Python Installer offers an easy option to install the required SSL root certificates. Because crash uses Python, this is the right choice to resolve the problem durably.

In order to install the SSL root certificates retroactively, you can use a command like:

/Applications/Python 3.11/Install Certificates.command