That's a generic error message that shows on all errors. Can you find the error message from your System->Log screen?
1. Go to your nopCommerce Administration section.
2. Go to System -> Log
3. Find the log entry that happened around the same time that the error occurred. This may be off by a few minutes depending on how synchronized your clocks are. It may also be off by a few hours if your timezone is not set correctly.
4. Click the View button to see the details
For more details around this error message, see my blog post at:
https://nopninja.com/were-sorry-an-internal-error-occurred