DB Error after upgrading
It looks like your image table field_data_field_image is not having the field_image_alt column. Which is strange, since Drupal creates that by default. 

Are you sure you ran update.php after migration? Do that first. If so, then try these steps.

I guess the best thing to do would be installing devel module and then with devel reinstall the image module. (Make backups as you might lose data!)

If that doesn't work you could add the column manually, and hope it was only this column that was off. See the following image for the fields you should have.