The following properties are available on the attachment controls:

The Web.config entries are available in the following locations and can be changed according to business requirements:
<install drive>:\Program Files (x86)\K2 blackpearl\K2 smartforms Designer\Web.config

<install drive>:\Program Files (x86)\K2 blackpearl\K2 smartforms Runtime\Web.config

• Blacklist - This entry is for the global Blacklist containing dangerous or unwanted file types. These file types can be maintained in the Web.config file to include additional or remove existing limitations. These files will be restricted at runtime.
• MaxSize - This entry is for the attachment controls file upload restrictions. The value of this entry is used to restrict all uploads to a specific limit to allow for standardized files and file management and is measured in kilobytes (KB). This size relates directly to the Max Size property of the File Attachment and Image Attachment controls. The default maximum size is 5120 KB. To configure a larger size in the control's property, update this entry as the value of the MaxSize entry in the Web.config file overrides the value in the control's property. For example, if you want to upload files of a maximum of 10 MB in the Attachment control, the MaxSize entry in the Web.config file would be 10000.

The following table is a list of Blacklist file types. These file types cannot be uploaded to the K2 server via the Attachment control. See the Backwards Compatibility section for details on releases prior to K2 smartforms 4.6.11.

Rules can be used to set file types and sizes at runtime such as the Set a control’s properties rule action. See the Control and Form Properties Actions topic for more detail.

• The global maximum File and Image size that can be attached is dictated by the following setting in the Web.config file in the system.web section.

  <httpRuntime maxRequestLength="16384" />

  When creating a Form that consists of many Views and multiple States the Form rules might not be visible after adding an additional State. This occurs when the Form definition increases and exceeds the Maximum Request Length specified in the Web.config. The maxRequestLength can be edited to enlarge the size of the Form definition. The default maximum value is set as 16384 KB (kilobyte) which is an integer value and can be changed to the required value in kilobytes. See the following link for more details about the maxRequestLength setting: https://msdn.microsoft.com/en-us/library/system.web.configuration.httpruntimesection.maxrequestlength(v=vs.110).aspx
  The Web.config file is found in the following locations:
  <install drive>:\Program Files (x86)\K2 blackpearl\K2 smartforms Designer
  <install drive>:\Program Files (x86)\K2 blackpearl\K2 smartforms Runtime
  

• The runtime maxRequestLength setting in the Web.config file overrides the MaxSize setting in the Web.config file and the Max Size control property setting.

• requestFiltering is a feature that can be configured in Internet Information Services (IIS).

  <system.webServer>

  <security>

  <requestFiltering>

  <requestLimits maxAllowedContentLength="1073741824"></requestLimits>

  </requestFiltering>

  </security>

  </system.webServer>

  See the following link for more detail: https://www.iis.net/configreference/system.webserver/security/requestfiltering/requestlimits

  If this setting is enabled on your environment, it is important to note that the minimum value of the maxRequestLength setting, the requestFiltering setting and the MaxSize setting will limit the attachments upload.

• Restricted file types are listed in the Blacklist.
• The Blacklist overrides the file types configured in the Allowed Types property. If a file should be allowed and is configured in the Allowed Types control property, the file type should also be removed from the Blacklist if listed there.

Beginning with K2 smartforms 4.6.11, previously allowed files may now not be allowed due to the inclusion of the Blacklist feature. To update the Blacklist to include or remove certain files, see the Web.config entries section of this topic. Change the Web.config file to exclude those files you want to upload and include files that should be restricted. Following is a list of Blacklist files restricted prior to K2 smartforms 4.6.11. This restriction was not previously configurable.

cpl, vxd, cmd, pif, com, msi, scr, ps, wsh, ocx, dll, bat, exe, vbs, vbe,.vb, aspx, vbscript, vscript, javascript, jscript, js.