warnings on login page after update to v3.1

Hi,
After updating I'm getting the two warnings below. Everything seems to be working fine but if anyone has any thoughts I'd appreciate it. thanks

Warning: array_merge() [function.array-merge]: Argument #1 is not an array in /my_install/plugins.php on line 46

Warning: Invalid argument supplied for foreach() in /my-install/plugins.php on line 48

Does anybody have an idea about this? I'm frequently getting errors when I try to edit modules created in v2.1. Could this be connected?

Can't find the upload.php? Below from Developer tools

Failed to load resource: the server responded with a status of 404 (Not Found)
jquery.min.js:5 POST atcourse.org/xerte2-1/editor/upload.php 404 (Not Found)

error_log
[18-Jan-2016 12:33:24 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 12:33:33 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 12:33:44 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 12:33:53 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:51:39 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:51:44 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:51:48 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:57:32 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:57:37 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:57:44 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:57:49 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:58:23 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:59:31 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:59:37 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[18-Jan-2016 13:59:41 Europe/Dublin] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 171
[22-Jan-2016 18:50:40 Europe/Dublin] PHP Warning: rename(/home2/u557956/public_html/atcourse.org/xerte2-1/,/home2/u557956/public_html/atcourse.org/xerte2-1/.1) [<a href='function.rename'>function.rename</a>]: Invalid argument in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 60
[22-Jan-2016 18:50:40 Europe/Dublin] PHP Fatal error: Call to a member function asXML() on a non-object in /home2/u557956/public_html/atcourse.org/xerte2-1/editor/upload.php on line 72

around line 43 of config.php is development set to true or false?
try setting to false and then refresh e.g.
$development = false;
Might not be the long-term answer but not sure why you are seeing those errors.
Ron

Hi Ron,
Thanks for your answer. It was already set to false. Any other thoughts? Whatever the problem is it is preventing me edit any of the content created in version 2.1. That's putting me in a tight spot as we are launching our course next week.
Thanks again,
Karl

Edit: Actually not an issue with all the content created in version 2.1. I can save and edit some learning objects and not others. I'm not seeing a pattern (in terms of page types, content etc though),

Hi Karl
are you using git to pull the code to your server? Try downloading 3.1 from here on the community site and extract that zip over the top of your code - obviously backup first!
I've not seen this particular error on any of the installations I look after and I'm not even sure whether the plugins functionality is in use but this might be an issue from a specific revision in git.
HTH
Ron

Hi Ron,
Thanks for your help with this so far. I downloaded Xerte 3.01 from Github and overwrote the files on the server (except auth-config.php, flatwhite.css and rloObject.html). I'm still having the problem though. See the screen shots and error log below. Any ideas? It is on a cloud hosting site.

From error log
/home2/u557956/public_html/atcourse.org/xerte2-1/plugins.php on line 48
[28-Jan-2016 13:02:08 Europe/Dublin] PHP Warning: array_merge() [<a href='function.array-merge'>function.array-merge</a>]: Argument #1 is not an array in /home2/u557956/public_html/atcourse.org/xerte2-1/plugins.php on line 46
[28-Jan-2016 13:02:08 Europe/Dublin] PHP Warning: Invalid argument supplied for foreach() in /home2/u557956/public_html/atcourse.org/xerte2-1/plugins.php on line 48
[28-Jan-2016 13:02:11 Europe/Dublin] PHP Warning: session_start() [<a href='function.session-start'>function.session-start</a>]: Cannot send session cache limiter - headers already sent (output started at /home2/u557956/public_html/atcourse.org/xerte2-1/plugins.php:46) in /home2/u557956/public_html/atcourse.org/xerte2-1/auth_config.php on line 45
[28-Jan-2016 13:04:14 Europe/Dublin] PHP Warning: array_merge() [<a href='function.array-merge'>function.array-merge</a>]: Argument #1 is not an array in /home2/u557956/public_html/atcourse.org/xerte2-1/plugins.php on line 46
[28-Jan-2016 13:04:14 Europe/Dublin] PHP Warning: Invalid argument supplied for foreach() in /home2/u557956/public_html/atcourse.org/xerte2-1/plugins.php on line 48
[28-Jan-2016 13:04:14 Europe/Dublin] PHP Warning: session_start() [<a href='function.session-start'>function.session-start</a>]: Cannot send session cache limiter - headers already sent (output started at /home2/u557956/public_html/atcourse.org/xerte2-1/plugins.php:46) in /home2/u557956/public_html/atcourse.org/xerte2-1/auth_config.php on line 45