@lord_alan By default few expensive operations on demo site has been prohibited, Extension store is one among them. Observed that on local instance this works fine screen. Please do share me the screen-shot on local instance where your facing this issue.
If I turn on error reporting I get this when loading the Extension Store:
Fatal error: Uncaught Error: Call to undefined method Settings_ExtensionStore_Extension_Model::unsetPassword() in /var/www/html/vt-720/modules/Settings/ExtensionStore/views/ExtensionStore.php:61 Stack trace: #0 /var/www/html/vt-720/modules/Settings/ExtensionStore/views/ExtensionStore.php(22): Settings_ExtensionStore_ExtensionStore_View->init() #1 /var/www/html/vt-720/includes/main/WebUI.php(184): Settings_ExtensionStore_ExtensionStore_View->__construct() #2 /var/www/html/vt-720/index.php(20): Vtiger_WebUI->process(Object(Vtiger_Request)) #3 {main} thrown in /var/www/html/vt-720/modules/Settings/ExtensionStore/views/ExtensionStore.php on line 61
Now. If you look in the pkg/vtiger... tree and examine the ExtensionStore view class you will see that there is no call to the unsetPassword method.
@uma.s If you download the ExtensionStore module package zip file from packages/vtiger/marketplace/ExtensionStore.zip however, and look at the same view class you will see the call to unsetPassword!!!
So I do not know how you managed to install your vtiger system but it didn't unpack the module package. It is different from the code in: