After Upgrading 3.x to 4.x i get error "Not found" everywher

[Maxtor]

After upgrading entire forum from 3.x to 4.x latest version, i can normally see first page of forum , but wherever i click i see this error:

 

http://prntscr.com/gd6t4j

What is wrong? Need help.

[Nathan Explosion]

Would need your site url for testing.....but wouldn't be surprised if it was related to url rewrites.

If your url is: http://www.site.com/forum/kjhdjahsdjkahsd then does this version work: http://www.site.com/index.php?/forum/khdahsdjkahdjhad ?

[Maxtor]

8 minutes ago, Nathan Explosion said:

Would need your site url for testing.....but wouldn't be surprised if it was related to url rewrites.

If your url is: http://www.site.com/forum/kjhdjahsdjkahsd then does this version work: http://www.site.com/index.php?/forum/khdahsdjkahdjhad ?

You are right, it was enabled mod rewrite , i had to create a new htaccess file .