Error: "The attachment cannot be accessed the file may have been modified outside of Act!" when adding attachments to an Opportunity June 06, 2019 14:21 Symptom: Error: "The attachment cannot be accessed the file may have been modified outside of Act!" when adding attachments to an Opportunity Product Details: Product Family: Act! Product: Act! Premium Version: v18.1 Update 3 Environment: OS: Windows 10 Cause: There is no known cause for this issue. Solution: Close Act! Reopen Act! and test issue Related articles How to attach a document to a Contact, Group, Company, or Opportunity in Act! How to uninstall the Act! Premium (access via web) Outlook Integration Changes to the Scope of Support for Act! Error: "Value cannot be null. Parameter name: value" or the Act! Toolbar displays words instead of icons when trying to work with Notes How do I install Act! v22?