Fatal error: Unsupported operand types in field.info.inc I'm cloning my client's drupal 7.15 site from online to my localhost. I received a copy of site folder and a copy of a sql dump file. I installed them into my localhost.

When I run the site, firstly I encountered the error:


  Fetal error: Class name must be a valid object or a string in
  C:\xampp\htdocs\mysite\includes\common.inc on line 7679


But the error went away when I did clear all cache tables manually via phpMyAdmin.
Unfortunately, the next error appeared.


  Fatal error: Unsupported operand types in
  C:\xampp\htdocs\mysite\modules\field\field.info.inc on line 294


[Edit]
I installed Drush and navigated to my site in Drush command line, but I could not run commands except "drush" because of that error.


  C:\xampp\htdocs\mysite>drush user-login
  Drush command terminated abnormally due to an unrecoverable error.       [error]
  
  Error: Unsupported operand types in
  C:\xampp\htdocs\mysite\modules\field\field.info.inc, line 294
  
  C:\xampp\htdocs\mysite>drush status
  Drush command terminated abnormally due to an unrecoverable error.       [error]
  
  Error: Unsupported operand types in
  C:\xampp\htdocs\mysite\modules\field\field.info.inc, line 294
  
  C:\xampp\htdocs\mysite>drush cache-clear
  Drush command terminated abnormally due to an unrecoverable error.       [error]
  
  Error: Unsupported operand types in
  C:\xampp\htdocs\mysite\modules\field\field.info.inc, line 294


When I traced into field.info.inc, I found that $instance['settings'] ( of the first parameter of _field_info_prepare_instance ) is missing for the field field_tags. Thus, the "+=" operation for arrays failed.

print $instance
Array
(
    [id] =&gt; 5
    [field_id] =&gt; 3
    [field_name] =&gt; field_tags
    [entity_type] =&gt; node
    [bundle] =&gt; article
    [deleted] =&gt; 0
)
print $instance["settings"]

****************
print field_info_instance_settings() call on taxonomy_term_reference
Array
(
    [user_register_form] =&gt; 
)
Your problems indicate that the copy did not come out right. Rather than try to diagnose the symptom, start over and copy the site again from scratch. If you can use Drush, perhaps Drush rebuild would help.  You could also use the drush rsync and drush sql-sync commands directly.