If you have an ABAP runtime error DBIF_RSQL_INVALID_REQUEST on your SAP system, check here the solution.

The error is as below:

Runtime Errors DBIF_RSQL_INVALID_REQUEST Invalid Request. What Happened? The current ABAP/4 program terminated due to an internal error in the database interface. What can you do? Make a note of the actions and input which caused error. To resolve problem contact your system administrator. You can use transaction ST22 (ABAP dump analysis) to view and administer termination messages, especially those beyond their normal deletion date. Error analysis In a statement an invalid request was made to the database interface when accessing table ""DOKTL"". 

Solution Windows install loop back adapter

You need to install the MS Loopback Adapter, check here how to do it.

Solution Linux check /etc/hosts file

Check if localhost exists on the file /etc/hosts, if not add it. You will also need to add your hostname and host ip in the /etc/hosts

127.0.0.1 localhost
192.168.XX.XX hostname

Where 192.168.XX.XX is the server IP address, remember not all internal IPs starts with 192.168....