Hello everyone,
I request support for a problem of importing users.
I use CBJUICE V2-3.1.6 on Joomla! 2.5.21

I want to import about 20 users with mail notification, but the procedure always hangs after importing 9/10 users.

The only video message, which appears after about 40 seconds is:
"Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator at root@localhost to inform them of the time this error occurred, and the actions you performed just before this error.
More information about this error may be available in the server error log."

What the problem?
I attach the CSV file used for the operation.

Thanks in advance. Carmine.

I don't have a 2.5 install to test it on.
The file imported fine without modification in Joomla 3.9 in a Windows sandbox after I added your user group and CB field.
You could try older versions of CBJuice.
Also try changing the CSV file line endings to Unix in Notepad++ ( Edit >> EOL Conversion >> Unix )
Encoding is correct (UTF-8)

Hi wolverton, thanks for support.
I edit the end-of-line character using Notepad++ but the import always stops at the record: demo20, and there is "Internal server error"

In your email you mention that it only happens when email notification is turned on. This would suggest an issue with your server or mail setup.
I would suggest that you try using an external SMTP provider.

Hi wolverton, we checked the mail server settings. There is nothing wrong.
At this point, I think there is a bug in the plugin code.

Thanks for support.

There could be an email throttle on the server causing the problem. Who provides your web hosting?
If you're only going to be importing 20 users, you could simply break the CSV into two parts and import twice.
Since this is the old 2.5 version that we no longer support, I'm reluctant to set up a sandbox site for it.