Seen in IE9 at least, possibly other IEs, but not in Chrome:
Attempting to upload a file at http://test2.wikipedia.org/wiki/Special:UploadWizard in the Upload step UW hangs with the message "Getting file information and previews..."
In the Console is the error "SCRIPT5007: Unable to get value of the property 'date': object is null or undefined" and load.php?debug=false&lang=en&modules=jquery%2Cmediawiki%2CSpinner%7Cjquery.triggerQueueCallback%2CloadingSpinner%2CmwEmbedUtil%7Cmw.MwEmbedSupport&only=scripts&skin=vector&version=20121126T175337Z, line 45 character 75
Note: I have not seen this, but a user reports that sometimes the UW page does not load at all, and when that happens IE reports an error LOG: Exception thrown by ext.uploadWizard: 'UploadWizardConfig' is undefined ReferenceError: 'UploadWizardConfig' is undefined
Version: unspecified
Severity: critical