It shows something like (they are strange character I don't have in my keyboard):
Perhaps you have some garbage bytes at the beginning of the file. Delete the first few bytes, save the file and try it.
And if you don't have a question mark on your keyboard but you have the alphabetic characters and numbers then you need to post info about what character set you are using and what keyboard you have.
Also make sure that your tnsnames.ora is not appended as ".txt" extension. It should not be like tnsnames.ora.txt. If this is the case, remove ".txt" from it.
Thanks for answering, unfortunately I did not well specified the situation, but I don't have any character at the beginning, it's the first thing I checked
I have even tried several solutions, like leaving or removing the stardard comment at the beginning:
# tnsnames.ora Network Configuration File: Oracle Client Path\NETWORK\ADMIN\tnsnames.ora
# Generated by Oracle configuration tools.
But it makes no difference.
Anyway I checked an ASCII map and the characters that appear are ï»¿
ASCII numbers: 139, 175 and 168
The file is Dos\Windows format and charset is UTF-8 (this is what Notepad++ says).
My keyboard is Italian (but I don't think it makes no difference) and I have modified the language of SQL Developer adding:
Into the sqldeveloper.conf file. But I already checked this too and it makes no difference to remove them (having SQL Developer in Italian as the OS)
Did yo make sure that you do have ".txt" appended to the file? Check the following metalink note: It has couple of other things apart from one I suggested to check.
Getting Junk Characters in Drop Down List for TNS Service Name (Doc ID 882357.1)
Unfortunately I don't have access to Metalink currectly, but I will ask for one account and check. Even if, as far as I understood googling it seems to be a problem related to JDBC (that as far as I know SQLDev uses and maybe it's related. But for the moment it seems I am the only one having this problem in SQLDev).
Meanwhile if you mean that I don't have to have a file like tnsnames.ora.txt I confirm you my file is tnsnames.ora