warning: array_merge() error on edit order

I didn't encounter this issue yet. Does the attached patch fixes the issue for you?

Else, I will look into this issue more closely later this week.

Thanks for reporting back the patch solves a part of your issue. I don't receive the second warning in my local installation. This message doesn't give me enough clues to know what's going wrong. What kind of fields did you added with Extra Fields Pane?

Could you replace the code of the function db_escape_string() at /includes/database.mysql.inc with the following code and post the output of the debug code here?

/**
 * Prepare user input for use in a database query, preventing SQL injection attacks.
 */
function db_escape_string($text) {
  global $active_db;
  if (is_array($text)) {
    $debug = debug_backtrace();
    print '<pre>';
    print_r(get_defined_vars());
    die();
  }
  return mysql_real_escape_string($text, $active_db);
}

debug_backtrace() will give information about which functions were called that finally result into the warning.

The patch in #1 has been committed.

@marcus178
Can you provide more information for the second error you got? See #3 for instructions.

It looks like the error message is caused by the UberCart MailChimp module. The Ubercart order object contains (among more) the following:

[uc_mailchimp] => Array
  (
    [29a6e9d8c0] => 1
  )

When Ubercart saves the order, it tries to save this value directly into the uc_orders table:

currency = '%s', uc_mailchimp = '%s'WHERE order_id = %d

[30] => GBP
[31] => Array
  (
      [29a6e9d8c0] => 1
  )
[32] => 164

which results into the mysql_real_escape_string() warning.

You should look for a solution for this problem in the UberCart MailChimp issue queue.
For example, in these issues:
#1218872: UC Mailchimp appears to be cause of error found here, mysql_real_escape_string() expects parameter 1 to be string
#1242030: An update of uc_mailchimp (add interest groups, merge vars, tidy up review order and fix mysql_real_escape_string() error)

I mark this issue as fixed, since the array_merge() bug in Extra Fields Pane has been fixed.

Never mind. Thanks for reporting the bug! :)