https://community.appian.com/discussions/f/rules/11145/appian-fails-to-validate-expression-sometimeswhile i was writing an expression rule for mni call, i realised that appian sometimes fails to validate the expression, i tried to enter many &quot;!!!!!...&quot; in expression and appian still validated the expression. Below is the screenshot for referenceen-USTelligent Community 12https://community.appian.com/thread/48914?ContentTypeID=1Wed, 27 Sep 2017 14:48:16 GMTd3a83456-d57b-489c-a84c-4e8267bb592a:bae01d58-051d-4d52-877f-64be8572dbdcvijaydAgree with Sandeep, it only validates the syntax. You will find so many combination where the expression is invalid and Appian validates it. However when you try to run it you would receive an alert with the error details.<div style="clear:both;"></div>https://community.appian.com/thread/48909?ContentTypeID=1Wed, 27 Sep 2017 13:38:38 GMTd3a83456-d57b-489c-a84c-4e8267bb592a:c56086f5-8a68-4d0c-8e48-9ebacba4bde9lokeshki thought appian validations are enough capable of handling extra symbols added to expression, but i realised now, it doesn&#39;t handle this.<div style="clear:both;"></div>https://community.appian.com/thread/48903?ContentTypeID=1Wed, 27 Sep 2017 11:05:31 GMTd3a83456-d57b-489c-a84c-4e8267bb592a:ef6ec2bf-a25f-4f93-b7c1-4409715fbe70Sandeep DeshmukhHello <a href="/members/lokeshk">lokeshk</a> ,<br /> <br /> it is verifing only Syntax like missing braces or comma. Here you are trying to verify &quot;tp! and Pv!&quot;<div style="clear:both;"></div>