Authentication failed almost always means the key itself, not your code. First, confirm the PATRONUS_API_KEY environment variable is actually set in the process that runs the SDK (a .env file that never gets loaded is the classic miss). Second, check the key is still valid: keys can expire or get revoked, and generating a fresh one in Patronus settings under your profile fixes that. Third, make sure there is no whitespace or quoting mangling the value when you export it. If a fresh key in a cleanly exported variable still fails, you may be pointing at the wrong Patronus environment.

Context: My Patronus integration returns "Authentication failed". I set the PATRONUS_API_KEY environment variable. How do I debug this?