Let's say the following is in the HPEL or SystemOut log when attempting to start your WebSphere network deployment manager (dmgr), node, or application server.

HMGR0149E: An attempt to open a connection to core group DefaultCoreGroup has been rejected.
The sending process has a name of your_cell\your_node\dmgr and an IP address of x.x.x.x.
Global security in the local process is Enabled.
Global security in the sending process is Enabled.
The received token starts with ??????^[^K?<?P?.?)^X^Y-??DQ.
The exception is com.ibm.websphere.security.auth.WSLoginFailedException: Validation of LTPA token failed due to invalid key or token type.

I experienced this event after adding a self-signed certificate to the node default keystore. The name of my self-signed certificate was "testing".

This caused the status of the node and the application servers in the node to be unknown (question mark icon) in the dmgr.

To resolve this, I did the following.

1. Delete the "testing" self-signed certificate.
2. Stop the application servers in the node.
3. Stop the node.
4. Stop the dmgr.
5. Start the dmgr.
6. Sync the node with the dmgr.
7. Start the node.
8. Start the application servers in the node.