Turn off file validation
This `REG_DWORD` value controls Office File Validation when Excel opens files.
since 0.9.8.11
Purpose
Show registry keys (1)
HKCU\software\policies\microsoft\office\16.0\excel\security\filevalidation\enableonload
This REG_DWORD value controls Office File Validation when Excel opens files. File validation compares the structure of Office 97–2003 binary documents with the expected file-format schema before Excel opens them.
A value of 0 turns file validation off. Excel then does not apply this protection to affected binary workbooks and templates. A value of 1 turns file validation on.
In the corresponding Group Policy setting, 0 represents the Enabled policy state because the policy is phrased negatively: enabling “Turn off file validation” disables validation. The Disabled policy state uses 1 and leaves validation enabled.
Notes
Security
Office File Validation is intended to detect malformed or deliberately altered binary files whose internal structure does not conform to the applicable file-format rules. Such structural changes can be used in file-format attacks that target vulnerabilities in Office file processing.
With enableonload = 0, affected Excel files bypass this check. A specially crafted binary file can therefore reach the normal file-processing code without first being detected by Office File Validation. Independent controls such as File Block policies, Protected View, antimalware scanning, and security updates remain in effect, but they do not necessarily provide the same structural validation.
File validation checks the document format. It is not a general malware scanner and does not by itself control macro execution, file permissions, or every condition that causes a document to open in Protected View.
Possible side effects
When file validation is enabled, legitimate legacy Excel files can also fail validation if they are damaged or were produced with a nonconforming internal structure, including files generated by some third-party software. The action Excel takes after a validation failure can depend on separate Excel security settings.
Turning validation off prevents warnings or protective behavior caused specifically by this check. It does not repair the file or establish that the file is safe; it only bypasses validation.
Notes
This is a per-user Excel setting. It does not disable Office File Validation in other Office applications or turn off Protected View as a whole.
The value controls whether validation occurs. The handling of a document that fails validation is governed by separate settings, particularly “Set document behavior if file validation fails.”
The 16.0 policy branch is also used by products newer than Office 2016 that share this Office policy generation, including supported Microsoft 365 Apps and Office LTSC releases.
Microsoft documentation
Microsoft Learn: Microsoft 365 Apps for Enterprise security baseline settings reference
Microsoft Learn: Microsoft Security Advisory 2501584 – Release of Microsoft Office File Validation