Hi I have a regular uploadField where I use:-

   function getCMSFields()
    {
        $fields = parent::getCMSFields();
		$uploadField = new UploadField( $name = 'RotaFile', $title = 'Upload rota excel file' );   
        	$uploadField->setFolderName('/adminfiles/rota_uploads');
   	        $uploadField->setAllowedExtensions(array('xlsm','xlsx'));
		$sizeBytes = 3 * 1024 * 1024 ; // 3 MB in bytes
		$uploadField->getValidator()->setAllowedMaxFileSize($sizeBytes);
		$uploadField->setCanPreviewFolder(true);
          	$fields->addFieldToTab( 'Root.ExcelUpload', $uploadField);
		return $fields;
    } 

uploadField validation passes and returns valid - but it then goes into dataobject::write(...) to do a second validation check which fails with "Forbidden" because xlsm is not in the "global" allowed list.

I see in databobject::write(...)

if(Config::inst()->get('DataObject', 'validation_enabled')) {
			$valid = $this->validate();

So it's doing a second check (that I don't really want) on the allowed extensions which fails as it just uses the global list which has no xlsm in it..

Can I switch `validation_enabled` off just for this one uploadFile object?
- or do I need to add xlsm file type to my global list of allowed extensions (using File and allowed extensions in _config.yml)?

thanks as ever!
Martin

Best thing to do is append the list of allowed_extensions in your config.

File:
allowed_extensions:
- xlsx