500 Internal Server Error SAP portal issue

Hi experts,

I would like to ask you for help with sap portal issue.

When I open the irj portal, I get a 500 internal server error.

I checked the RFC, certificates, users, connections, parameters in DEFAUPT.PFL and CentralInstance.PFL ... etc.

This system was installed with the export / as a copy of the system / I compared both systems and I can't find any difference.

Where could be the problem?

Thank you in advance for all the advice

Miriama