Connection problem: LwM2M Server Internal Error 5.00


I am using

I have registered the device (.csv file) and added protocol according to the manual: LWM2M - Cumulocity IoT Guides .

My device is trying to register to coap://, but gets response from Server: Internal server error 5.00.

The same situation is with:



The attempt to reach bootstrap server, was successful, but after redirection to, the connection can not be established due to server error as described above.

Still I can successfully communicate to other servers, like:, so I wonder if there is any problem on device side.

Please let me know any possible solutions as soon as possible.
Thanks in advance.