If you encounter the error "Condition not valid" this typically indicates that an entry you are trying to sync into Outlook contains a value that is considered too long and possibly malformed.
For example, when syncing Google tasks to Outlook if the title of the task contains more than 200 characters then this likely will cause a sync failure. Similarly, when syncing Google calendar events to Outlook if the subject of the event is longer than 200 characters this too can trigger an error. Event subject and task titles should be short while the details are contained within the body of the entry.
In most cases the name of the failed entry will be noted in the gSyncit error message. You will need to manually locate the entry and correct it. If the name of the entry is not contained in the error message then move the error dialog to the side and check the status dialog for the title of entry.
If this issue happens when syncing calendar events then check the subject of the event. If this issue happens when syncing tasks check the title of the task. If this issue happens when syncing contacts check the name, company and emailaddress for the contact.