Filebased datasource security

Are you seeing this error when using a file based datasource like excel in webplayer.?

The data source may be missing or has been changed.

This generally happens for one of the following reasons
First from a security perspective spotfire ensures that you cannot just open any file, you need to provide a white list of locations that should be accessible to the webplayer. Change the property for your case in the web.config file.
This is controlled by two settings in the web.config 

AllowedFilePaths 
Provide the full path to directories or files on a 
local disk, other than the Spotfire Web Player 
installation directory, that you want to access 

in the Spotfire Web Player.
Specify each file or directory in a separate 
<string> tag. 
For example:
<value> 
 <ArrayOfString> 
 <string> 
 C:\MyData\ 
 </string> 
 <string> 
 C:\Logs\spotfire.txt 
 </string> 
 </ArrayOfString> 

</value>

AllowedWebRootFiles 
Provide the full path to files stored in the 
Spotfire Web Player installation directory or 
any of it’s subdirectories that you want to 
access from the Spotfire Web Player. Separate 
entries with a semi-colon (;). All paths are 
relative to the webroot directory. For 
example C:\Program 
Files\Tibco\Spotfire Web Player\6.5\
Example: 
<value> 
 ..\Logfiles\PerformanceCounter.txt; 
 ..\Logfiles\Spotfire.Dxp.Web.log 

</value>

if you have done both these steps and still cannot access the file, then potentially the userid used for webplayer identity doesnot have access to the location.. so ensure that and the last option but it may be true is ensure that the location where you are expecting the file is accessible from your webplayer server too, you may have mapped a network location to H drive and now the webplayer is looking for H drive which is not mapped..  in those cases use network paths rather than mapped drives \\networkshare\mydatafolder\salesdata\ 

Hope this helps folks out there...