Troubleshooting Group Policy

Administrator Enters Invalid Values
Group Policy administrative tools, such as the Group Policy Editor and the Group Policy Management Console, do not perform custom validations, so they will allow an administrator to enter an invalid value in a string field, such as an incorrect type name.

Only policies having valid values on all settings are applied, so when an invalid value is detected, an entry is written to the event log and the entire policy is ignored. The problem is logged to the event log.

Application Is Modified Without Generating New Group Policy Template
If the application is modified, some configuration elements may be replaced with new elements that have the same names, but different types. In this case, the manageable configuration source will look for the policies of the new element, but it will find policy settings for the original configuration elements, which may not match. Typically, this will result in missing values.

Policies Conflict to Produce Invalid Configuration
It is possible for different policies to conflict with one another. If this is the case, it will result in an invalid configuration after the Group Policy overrides are applied. This type of problem can easily occur, because different polices may be applied in different Group Policy Objects. In this case, the ManageableConfigurationSource instance does not detect an error. Typically, the consumer of the configuration settings logs the error.