Today our site went down with only white pages showing. The logs from the nginx server looks like this:
[01-Sep-2016 10:33:15] WARNING: [pool www0] child 26970 said into stderr: "NOTICE: PHP message: PHP Fatal error: Class 'MigrateSimpleFieldHandler' not found in /srv/www/mysite/public_html/sites/all/modules/entityreference/entityreference.migrate.inc on line 18"
[01-Sep-2016 10:33:15] WARNING: [pool www0] child 26970 said into stderr: "NOTICE: PHP message: PHP Fatal error: Class 'MigrateUIWizard' not found in /srv/www/mysite/public_html/sites/all/modules/migrate_d2d/migrate_d2d_ui/migrate_d2d_ui.migrate.inc on line 18"
[01-Sep-2016 10:33:20] WARNING: [pool www1] child 26712 said into stderr: "NOTICE: PHP message: PHP Fatal error: Class name must be a valid object or a string in /srv/www/mysite/public_html/includes/common.inc on line 8026"
[01-Sep-2016 10:33:24] WARNING: [pool www1] child 26710 said into stderr: "NOTICE: PHP message: PHP Fatal error: Class name must be a valid object or a string in /srv/www/mysite/public_html/includes/common.inc on line 8026"
[01-Sep-2016 10:34:27] WARNING: [pool www1] child 27190 said into stderr: "NOTICE: PHP message: PHP Fatal error: Class name must be a valid object or a string in /srv/www/mysite/public_html/includes/common.inc on line 8026"
[01-Sep-2016 10:34:40] WARNING: [pool www1] child 26712 said into stderr: "NOTICE: PHP message: PHP Fatal error: Class name must be a valid object or a string in /srv/www/mysite/public_html/includes/common.inc on line 8026"
[01-Sep-2016 10:34:56] WARNING: [pool www0] child 23319 said into stderr: "NOTICE: PHP message: PHP Fatal error: Class name must be a valid object or a string in /srv/www/mysite/public_html/includes/common.inc on line 8026"
This happens as soon as I try to update the database, I also get a "502 Bad Gateway" message from the server just before the screen turns white.
Should I activate the deactivated modules again or uninstall them?
EDITED: I can also mention that according to the status report there are database updates waiting to be run, but when I do that locally (wamp) I get the message that no database update is required. When I try to do this db update on the web server (nginx) I get 502 bad gateway error and then the pages go blank.
NOTICE: PHP message: PHP Fatal error: Class 'MigrateSimpleFieldHandler' not found
have you deleted any of the module before uninstalling it?