When clicking on Magento Connect Manager from admin, facing this error: Mage registry key "_singleton/admin/session" already exists
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Try using full name of class instead of a modelized one. Helped in my case. – Roomy Feb 25 '15 at 19:46
I don't have a solution, but I can explain why/when this is happening.
TL;DR: In your case the model admin/session
is not instantiated or does not exist and Mage::getModel('admin/session')
returns false
Full explanation
There is a bug (or better yet an inconsistency) in the Mage::getSingleton
method.
It has been there for ages.
The method looks like this:
public static function getSingleton($modelClass='', array $arguments=array())
{
$registryKey = '_singleton/'.$modelClass;
if (!self::registry($registryKey)) {
self::register($registryKey, self::getModel($modelClass, $arguments));
}
return self::registry($registryKey);
}
Now let's take a look at the Mage::register
method
public static function register($key, $value, $graceful = false)
{
if (isset(self::$_registry[$key])) {
if ($graceful) {
return;
}
self::throwException('Mage registry key "'.$key.'" already exists');
}
self::$_registry[$key] = $value;
}
Notice the throwException
. It is exactly what you see as error message. If there is already a value in the registry for a certain key, you get an error.
In your case you get this error because there is already a value for key _singleton/admin/session
. This happens in one case.
Going back to the getSingleton
method, this is the bug/inconsistency:
if (!self::registry($registryKey)) {
This condition will return true
when the value you registered for a specific key is null, false, 0
.
This happens when getModel
returns false
. (when a model class is not found).
You should check if you have extensions rewriting the admin session class, or you can debug starting from the methods above to see why you are getting this error.
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I'm encountering the same issue with overriding
catalogSearch
class. I'm overriding in following way in global section config.xml of custommodule:<models> <catalogsearch> <rewrite> <layer>MY_Custommodule_Model_CatalogSearch_Layer</layer> </rewrite> </catalogsearch> </models>
– R T Oct 9 '15 at 6:50 -
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HI Marius, what would be the fix for this bug?
if (!self::registry($registryKey)) {
– snh_nl Nov 6 '17 at 9:44 -
1There shouldn't be a fix I think. you should just make sure that all your objects called via
getSingleton
are objects anyway – Marius♦ Nov 6 '17 at 9:56 -
Aha! I also saw LTS is suggesting a pull around this - maybe you are interested. github.com/OpenMage/magento-lts/pull/368 – snh_nl Nov 6 '17 at 15:22
If you have maintenance mode ON, make it off . clear cache. and retry to access Magento connect manager. Hope that will work.