After a private discussion with
@pop123 , I'm sharing our collaboration publicly as it may be beneficial for others
and resolved their problem.
@pop123 discovered a discussion detailing similar issues on Windows.
See
https://www.3cx.com/community/threads/server-error-trying-to-log-in-error-reading-key-ring.60168/
He shared the details of the solution with me and asked if there was an equivalent available in Linux.
I warned him that manipulating the 3CX files could worsen the problem. I had never performed this operation before.
@pop123 agreed to execute the procedure (adapted for Linux) despite the potential risks involved.

.
I sent him the command to copy files from /var/lib/3cxpbx/.aspnet/ and to delete the files;
In the end, it looks like this:
Bash:
sudo mkdir -p /root/3cxpbx/.aspnet/ && sudo rsync -avzh /var/lib/3cxpbx/.aspnet/ /root/3cxpbx/.aspnet/ && sudo find /var/lib/3cxpbx/.aspnet/ -type f -exec rm {} + && echo "Please wait ..." && sudo systemctl restart 3CXPhoneSystemMC01 && echo "Completed! Try logging into the 3CX Phone System web page." || echo "An error occurred."
Here's a description of what each command in the sequence does:
1. sudo mkdir -p /root/3cxpbx/.aspnet/:
- Creates the directory /root/3cxpbx/.aspnet/, including any necessary parent directories. The sudo ensures it runs with administrative privileges.
2. sudo rsync -avzh /var/lib/3cxpbx/.aspnet/ /root/3cxpbx/.aspnet/:
- Synchronizes files from /var/lib/3cxpbx/.aspnet/ to /root/3cxpbx/.aspnet/, preserving attributes like permissions and timestamps. sudo is used for permissions, -a ensures archival mode, -v for verbose output, -z compresses file data during transfer, and -h displays sizes in a human-readable format.
3. sudo find /var/lib/3cxpbx/.aspnet/ -type f -exec rm {} +:
- Searches for all files (type f) in /var/lib/3cxpbx/.aspnet/ and deletes each one (exec rm {} +). The sudo ensures it runs with root permissions.
4. echo "Please wait ...":
- Outputs "Please wait ..." to the terminal, providing a user-friendly message indicating that further actions are being processed.
5. sudo systemctl restart 3CXPhoneSystemMC01:
- Restarts the service 3CXPhoneSystemMC01, using sudo to ensure it has the necessary permissions.
6. echo "Completed! Try logging into the 3CX Phone System web page.":
- Outputs this message upon successful completion of all previous commands, suggesting that the user tries logging into the 3CX system web page.
7. || echo "An error occurred.":
- If any command preceding the || fails, it outputs "An error occurred." This is used for basic error handling to inform the user if something went wrong during the execution.
Glad to have helped solve the problem! Thanks for your patience
@pop123 .