Why isn’t my 3- license key working?

When attempting to enter your license key into Portainer Business Edition, that starts with 3-, you may encounter the following error message:

License is invalid

Cause

This issue arises when using versions of Portainer 2.18.3 or older. These previous versions do not support the 3- license key type.

Fix

To resolve this problem, upgrade your Portainer version to 2.18.4 or newer.
Upgrade instructions