Error message using Service Layer of SAP Business One

Hello to all,
We make an initial call for login to Service Layer of SAP Business One using the Post Request
URL: https://serveripaddress/ServiceLayer/b1s/v1/Login
Result: Success

But after the initial statement that completed successfully, we make a second call but failed with the above error message.
Get Request
URL: https://serveripaddress/ServiceLayer/b1s/v1/BusinessPartners?'$filter= contains(EmailAddress,‘[em]’)'SessionId=[SessionId] ’

Result: Sorry, we ran into a temporary bug and can’t complete your request. We’ll fix it as soon as we can; please try again in a bit!

Could you please assist us in order to resolve this issue?
Best Regards,
Spyros Papadogiannos