Resource not found error

[Deathopex]

Recently my server got exploited, so I've decided to test if it's vulnerable by myself. But the remote code execution didn't work, the server throwed an error when object sent. I guess the exploit demo doesn't work properly.

[HyCraftHD]

Well alone the log tells you that you are vulnerable to CVE-2021-44228.
Your JDK seems to be JDK9+ so com.sun.jndi.ldap.object.trustURLCodebase is set the false by default. Did you enable that to test it?
I'll update the proof of concept to be a bit more robust and meaningful in the future.

Either way, you do not need to test the RCE to check if the exploit has been fixed.