Workaround

1. If you limit your Salesforce Orgs and Profiles to specific IP Ranges, you must whitelist the Composer IP Addresses to each Profile that needs to use Conga Composer.
   For more information on how to whitelist Composer IP Addresses, see Add Conga Composer IP Addresses.
2. If you still get an error after whitelisting the Composer IP Addresses, you must check the Login History of the respective user and add the failed IP address as shown below:
   1. On the Salesforce homepage, click the gear icon () in the right corner and select Setup.
   2. Enter Users in the Quick Find box, then select Users.
   3. Click the respective User Name link.
   4. Go to the Login History section and check for Failure Status and the Source IP.

      
      
      

   5. Add the Source IP address into the respective user Profiles and Salesforce Org.