How to connect to Oracle 9i from SQL Developer 18

If you encounter to the following message ...

An error was encountered performing the requested operation:

ORA-00604: error occurred at recursive SQL level 1
ORA-01882: timezone region  not found
00604. 00000 -  "error occurred at recursive SQL level %s"
*Cause:    An error occurred while processing a recursive SQL statement
           (a statement applying to internal dictionary tables).
*Action:   If the situation described in the next error on the stack
           can be corrected, do so; otherwise contact Oracle Support.
Vendor code 604

... you can fix it by adding

AddVMOption -Duser.language=en
AddVMOption -Duser.region=us
AddVMOption -Duser.timezone="EET"

to your /ide/bin/ide.conf file.

Good Luck !!!