Since the last upgrade, the datepicker does not appear when creating or editing an event. Firefox Web Developer Tools reports these errors:

ReferenceError: January is not defined create-events:2002
ReferenceError: January is not defined create-events:2069
ReferenceError: January is not defined create-events:2174

Hi Alex,
It seems the upgrade process not taken place correctly.
Do you allow me to upgrade with latest?
Before that I would suggest you to have backup whole site.
Thanks

I have taken a full backup. You can try the upgrade again.

Hi Alex,
I am experiencing login failed at site admin panel.
Can you check please?
Thanks

We changed the admin password this morning. How can I send you the new password?

Hi Alex,
Sorry for the delay.
You can provide us by editing your first post of this topic.
Thanks

The Admin password has been updated in the first message.

Hi, Alex.

This issue may be caused by 3rd party scripts.
Please, change template to Joomla! default one and disable that tab module at right (with Twitter icons).
Then check if issue persist.

As you instructed, I disabled the (anything tabs) tabs on the right side and changed all community-related pages to rhuk-milkyway, then to Beez5 templates, cleared the server and browser caches each time, and the problem persisted.

I have reinstated the tabs and template to the previous settings so not to introduce too many changes at once.

Hi, Alex.

Ok, then I assign developer to this thread to take a look too...

Hi Alex,

seem you server doesn't support anonymous function
/components/com_community/libraries/fields/date.php line 181:

$monthNames = array_map(function ($item) {
            return "'" . $item . "'";
        }, $months);
        $monthNamesShort = array_map(function ($item) {
            return "'" . substr($item, 0, 3, 'UTF-8') . "'";
        }, $months);
        $dayNames = array_map(function ($item) {
            return "'" . $item . "'";
        }, $days);
        $dayNamesShort = array_map(function ($item) {
            return "'" . substr($item, 0, 3, 'UTF-8') . "'";
        }, $days);
        $dayNamesMin = array_map(function ($item) {
            return "'" . substr($item, 0, 2, 'UTF-8') . "'";
        }, $days);

$html .= "monthNames: [ " . implode(", ", $monthNames) . " ],\n";
$html .= "monthNamesShort: [ " . implode(", ", $monthNamesShort) . " ],\n";
$html .= "dayNames: [ " . implode(", ", $dayNames) . " ],\n";
$html .= "dayNamesShort: [ " . implode(", ", $dayNamesShort) . " ],\n";
$html .= "dayNamesMin: [ " . implode(", ", $dayNamesMin) . " ],\n";

$html .= "monthNames: [ 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December' ], monthNamesShort: [ 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec' ], dayNames: [ 'Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday' ], dayNamesShort: [ 'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat' ], dayNamesMin: [ 'Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa' ],";

monthNames: [ <?php echo implode(", ", $monthNames) ?> ],
monthNamesShort: [ <?php echo implode(", ", $monthNamesShort) ?> ],
dayNames: [ <?php echo implode(", ", $dayNames) ?> ],
dayNamesShort: [ <?php echo implode(", ", $dayNamesShort) ?> ],
dayNamesMin: [ <?php echo implode(", ", $dayNamesMin) ?> ],

monthNames: [ 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December' ], 
monthNamesShort: [ 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec' ],
dayNames: [ 'Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday' ],
dayNamesShort: [ 'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat' ],
dayNamesMin: [ 'Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa' ],

Hi Albertus,

Thank you for your quick response and suggested fix. However, when you told me my "server doesn't support anonymous function" I reviewed my server configuration carefully. NOTE: This will be useful for troubleshooting some of your user's environments.

On my server, I was using eAccelerator PHP opcode cache - which does not support anonymous functions. I did some research and It appears to have lost community support in 2012. I have disabled it and everything is working normally. I will be changing from eAccelerator to APC as it will be included in PHP 6. I think this is a better alternative than changing core code just for my site, which can cause issues during subsequent upgrades.

As you are using anonymous functions in your code, you may consider noting in your system requirements that you do not support servers using eAccelerator.

Thanks for your help!