How to Modify the Self-Service Portal Attachment File Size
By default, users can attach files in requests that they submit when they use the Self-Service Portal in System Center 2012 – Service Manager. However, the Self-Service Portal limits the attachment file size to 10 megabytes (MB). You can modify the Self-Service Portal default attachment file size by editing a property manually in the Web.config file.
The maximum file size that the Self-Service Portal supports is independent of the work item maximum size settings that are specified in the Service Manager console in the Administration workspace.
To modify the Self-Service Portal attachment file size
Log in to the computer that hosts the Web Content Server with administrative credentials.
Using a text editor of your choice (for example, Notepad), open the Web.config file in the %inetroot%\inetpub\wwwroot\System Center Service Manager Portal\servicehost folder.
Locate the <binaryMessageEncoding> section, as shown in the following example:
<binaryMessageEncoding> <readerQuotas maxArrayLength="10485760"/> </binaryMessageEncoding>
Modify the line <readerQuotas maxArrayLength="10485760"/> by replacing the maxArrayLength value with a value of your choice.
Close the text editor, and save the changes.