I am trying to connect SQL Developer with Oracle Database, but in the end again one error is showing again and again after clicking on "Test".
I tried it again after changing the Port to "1522" from "1521" but the same thing is happening, I am using Windows 10.
I have attached the screenshot as above.
Try to add following lines to %SQL_DEV_HOME%\sqldeveloper\bin\sqldeveloper.conf
AddVMOption -Duser.language=en
AddVMOption -Duser.country=US
Apart from this you can check few things:
Verify oracle xe database settings by executing this in sqlplus:
select userenv('LANGUAGE') from dual;
Result of this query can be ENGLISH_AMERICA.WE8MSWIN1252)
Change regional settings in control panel according to your database (For this example it can be changed to English (United States))
Change NLS parameters in sql developer according to your database and regional settings