The following are common SAP message when user is unable to connect to SAP. 


1) Lost of Database Connection



or 



This often due to lost of network connection or Windows permission. It can happen if,

- any changes in the Windows operating system or domain user profile that is configured to run the SQL database engine. 

- Possibly Windows security update has broken the network or Windows permission. 

- Unstable network or internet.

- SQL server failure, include insufficient harddisk space.

- Hardware failure include network card or router.


Troubleshoot: 


At the client PC, ping the Server name or IP Address of the SQL Server. Below is an example of a successful response.



Otherwise, you will receive failed request.


At the SQL Server, check whether the SQL database engine is running and logon to SQL Server Management Studio (SSMS) successfully.  



Resolution:

Please follow to restart the SAP system in below sequence and troubleshoot further.


     Shut down RDS Server (if applicable)  

     Shut down SAP Server

     Shut down SQL Server

     Start SQL Server

     Start SAP Server

     Start RDS Server


2) Lost of SLD (System Landscape Directory)



Please note the Port number varies depends on the version of SAP Business One.


Troubleshoot: 

Check whether the SLD is available by open below URL in web browser. 


     https://[SERVER NAME]:30010/ControlCenter/


You will see a logon screen to SLD, means the SLD is working.


Otherwise, the web browser will return 'Unable to connect' message.



Check whether the SLD Windows Service is running. Below is showing the SLD Windows Service has been stopped. 




Resolution:


- Start the SLD Windows Service and try logon again, or

- Restart the SAP Server 


Please contact your SAP Business One technical consultant for further assistance.