Switch from Windows to Linux, Cannot Modify Header errors

Yesterday we made a switch from Windows to Linux through GoDaddy and I believe that error messages appearing on the sites wp-login.php are associated with it. There are four lines:

Warning: Cannot modify header information – headers already sent by (output started at /home/content/88/9177388/html/datacentersummiteast-rtp/wp-content/themes/news/functions.php:1) in /home/content/88/9177388/html/datacentersummiteast-rtp/wp-login.php on line 349

Warning: Cannot modify header information – headers already sent by (output started at /home/content/88/9177388/html/datacentersummiteast-rtp/wp-content/themes/news/functions.php:1) in /home/content/88/9177388/html/datacentersummiteast-rtp/wp-login.php on line 361

Warning: Unknown: open(/var/chroot/home/content/88/9177388/tmp/sess_vuf6qluitcpmoih5g7c1qgihj3, O_RDWR) failed: No such file or directory (2) in Unknown on line 0

Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct () in Unknown on line 0

I know that it might have something to do with PHP not being able to write to the /tmp directory or a missing/tmp directory. I am not sure how to fix the lines in the wp-login and function php files and I am not sure about any other way to resolve the issue.