an internal error occurred clicking on shopping cart

when clicking on the shopping cart, we get this error on some specific user accounts.

We're sorry, an internal error occurred.

Our supporting staff has been notified of this error and will address the issue shortly.

We apologize for the inconvenience.

Please try clicking your browsers 'back' button or try reloading the home page.

If you continue to receive this message, please try again in a little while.

Thank you for your patience.

but not all accounts. some accounts are normal

I assume you are using latest nopCommerce version. You should enable debugging by setting the value in web.config and then see the logs to see the error details.

Please paste them here so we can know more about it.

Best Regards,
Anshul

Try to check error logs so you will get idea that from where its broken. on admin side you can check it at /admin/log/list or you can directly check on the database by firing query like SELECT * FROM [Log] ORDER BY ID DESC