The form was working production and there is an issue saying Notification email is getting and the error is
An unexpected error has occurred. [LFF502-UnexpectedError] Details: URL: Error: UnexpectedError Date: 5/23/2019 2:47:05 PM (Central Standard Time) HTTP Status Code: 500 Business Process ID: 574 Instance ID: 13573 Business Process Name: TAMUIT-HR Strategic Hiring Process Stack Trace: Caught exception: Laserfiche.Forms.CommonUtils.Exceptions.LFFormsException Message: An unexpected error has occurred. [LFF502-UnexpectedError] Inner exception: System.Xml.XPath.XPathException Message: Expression must evaluate to a node-set. at MS.Internal.Xml.XPath.XPathParser.ParseNodeTest(AstNode qyInput, AxisType axisType, XPathNodeType nodeType) at MS.Internal.Xml.XPath.XPathParser.ParseStep(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseRelativeLocationPath(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParsePathExpr(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseUnionExpr(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseMultiplicativeExpr(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseAdditiveExpr(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseRelationalExpr(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseEqualityExpr(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseAndExpr(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseOrExpr(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseExpresion(AstNode qyInput) at MS.Internal.Xml.XPath.XPathParser.ParseXPathExpresion(String xpathExpresion) at System.Xml.XPath.XPathExpression.Compile(String xpath, IXmlNamespaceResolver nsResolver) at System.Xml.XPath.XPathNavigator.Select(String xpath) at System.Xml.XmlNode.SelectNodes(String xpath) at Laserfiche.Forms.Routing.AttributeToken.ParseTokens(Boolean Encode, XmlDocument xmldoc, String inString, cf_users user, Boolean keepIfNoMatch, String TimeZone, Int32 pos, ConvertToLocalDateFormat ConvertToLocalDateFormat, Boolean translateTokens, Boolean escapeEncode, ICollection`1 fields, Boolean replaceNewlines, ParseTokenOptions tokenOption, Boolean retainCurrentUserToken, Boolean removeGroupSeparators, Int32 currentRow, Boolean useGregianCal, Int32 attempts) at Laserfiche.Forms.Routing.AttributeToken.ParseTokensEncoded(XmlDocument xmldoc, String inString, cf_users user, Boolean keepIfNoMatch, String TimeZone, Int32 pos, ConvertToLocalDateFormat ConvertToLocalDateFormat, Boolean translateTokens, Boolean escapeEncode, ICollection`1 fields, Boolean replaceNewlines, ParseTokenOptions tokenOption, Boolean retainCurrentUserToken, Boolean removeGroupSeparators, Int32 currentRow, Boolean useGregianCal) at Laserfiche.Forms.Routing.EmailService.Execute(Int32 instanceId, IRoutingContext routingContext, RoutingInstanceStatus OriginalStatus) at Laserfiche.Forms.Routing.ServiceTask.Execute(Int32 instanceId, IRoutingContext routingContext)
Can any say why this error is giving?