How to Solve Ords Issue : The request could not be mapped to any database.

 The request could not be mapped to any database. 

Check the request URL is correct, and that URL to database mappings have been correctly configured

this issue because the PDB in not Open 

Login as sysbda

and run 

alter pluggable database all open;

then
Stop ORDS App from tomcat and start it again 

Ords will work Fine Now