anyone can point what is wrong in my function

<cffunction name="handleFileUpload" access="private" returntype="any">
        <cfargument name="uploadDir" type="string" required="true">
        <cfargument name="photoField" type="any" required="false">
        
        <cfset var result = {
            files = [],
            errors = []
        }>
        
        <cfif structKeyExists(arguments, 'photoField') AND len(arguments.photoField)>
            <cfif isArray(arguments['photoField'])>
                <!--- Handle multiple file upload --->
                <cfloop array="#arguments['photoField']#" index="file">
                    <cfset var filePath = arguments.uploadDir & "/" & file.serverFile>
                    
                    <cfif file.fileSize GT 0 AND len(file.fileName)>
                        <cffile 
                            action="upload"
                            fileField="#arguments.photoField#"
                            destination="#arguments.uploadDir#"
                            nameconflict="makeunique"
                            accept="image/*"
                            result="local.uploadResult">
                        
                        <cfif structKeyExists(local.uploadResult, "serverFile")>
                            <cfset arrayAppend(result.files, {
                                fileName = file.fileName,
                                filePath = filePath,
                                serverFile = local.uploadResult.serverFile
                            })>
                        </cfif>
                    <cfelse>
                        <cfset arrayAppend(result.errors, {
                            fileName = file.fileName,
                            error = "No file selected"
                        })>
                    </cfif>
                </cfloop>
            <cfelse>
                <!--- Handle single file upload --->
                <cfset var filePath = arguments.uploadDir & "/" & arguments['photoField'].serverFile>
                
                <cfif arguments['photoField'].fileSize GT 0 AND len(arguments['photoField'].fileName)>
                    <cffile 
                        action="upload"
                        fileField="#arguments.photoField#"
                        destination="#arguments.uploadDir#"
                        nameconflict="makeunique"
                        accept="image/*"
                        result="local.uploadResult">
                    
                    <cfif structKeyExists(local.uploadResult, "serverFile")>
                        <cfset arrayAppend(result.files, {
                            fileName = arguments['photoField'].fileName,
                            filePath = filePath,
                            serverFile = local.uploadResult.serverFile
                        })>
                    </cfif>
                <cfelse>
                    <cfset arrayAppend(result.errors, {
                        fileName = arguments['photoField'].fileName,
                        error = "No file selected"
                    })>
                </cfif>
            </cfif>
        <cfelse>
            <cfset arrayAppend(result.errors, {
                fileName = "",
                error = "No files uploaded"
            })>
        </cfif>
        
        <cfreturn serializeJSON(result)>
    </cffunction>

error i am getting is: additional*Struct (ordered)*DetailstringErrorCodestring0Extended_InfostringExtendedInfostringMessagestringNo matching method for String.isSERVERFILE() found. there are no methods with this name.

You didn't give the full stack trace, but I'm assuming that

arguments['photoField']

is coming in as a string instead of s struct/object right after your else statement.

between i am passing multiple files to upload,so it should not go to the else clause

have you already validated the arguments are coming in as expected by doing a dump and then validate your if logic by dumping from within each if statement to confirm it is working as expected?

It's hard to say where the failure is, since the stack trace is cut-off, but with the limited about you gave us, it looks like it's on the else statement branch.

form should be

<form method="post" enctype="multipart/form-data">

i did that already

What datatype is 'arguments.photoField'? That looks like you're passing over a string, the name of the formfield. Yet what's this line?

<cfset var filePath = arguments.uploadDir & "/" & arguments['photoField'].serverFile>

Almost certain, this is your issue:

arguments['photoField'].serverFile

Is photoField a string, or a struct? You're referencing it as both. Note the error: "No matching method for String.isServerFile()" The string in this case is arguments['photoField']. A Java String datatype doesn't have 'isServerFile' as a function.