Symptoms

The sync tool fails and produces a log line like the following:

2016-12-12 10:30:11.5067|Error|ILST.Program|Error during Sync occurred: Index was outside the bounds of the array.

Cause 

This issue is typically a result of a problem with the encryption of passwords. This can be due to the passwords being encrypted twice, or the password containing an XML special character like & or <.

Actions

Customer Actions:

• Change password to something without special characters.
• Re-enter passwords in plain text in both the <Connection> and <CommunityAPI> sections of the config file. 
• Encrypt them again.