File transfer problems in OCS 2007 R2 Group Chat
After installing the Group Chat component from Office Communications Server 2007 R2, you may encounter the following error while attempting to upload or download files while joined to a chat room (see screenshot):
A file transfer error occurred. Server was unable to process request. —> Object reference not set to an instance of an object.
By default, the MGCWebService virtual directory in IIS is configured to automatically use Anonymous Access using the IUSR_<ComputerName> account, which is a member of the Guests group of the local machine. However, in looking at the NTFS permissions of the File Repository folder used by Group Chat, you will find that the Guests group is not found in its Access Control List (ACL):
To resolve this issue, change the account used for Anonymous Access in the properties of the MGCWebService to either the Group Chat Admin service account or the Group Chat Channel service account, as per the following TechNet article:
To configure the Web site settings in IIS7
- Open Internet Information Services (IIS) Manager by clicking Start, pointing to All Programs, pointing to Administrative Tools, and then clicking Internet Information Services (IIS) Manager.
- In the console tree, expand the local computer, expand the Web Sites folder, open the Web site (MGCWebService), and then Basic Settings.
- Click Connect as… Select Specific user: and Click Set
- Fill in the Group Chat Channel Server service account as DOMAINNAME\SamAccountname and password. Click OK.
- Click OK.Click Test Settings.. verify that all is OK and Click Close.
- Click OK.
- Restart IIS using an administrative command prompt and typing ‘iisreset /noforce’