UFO/AFO: Best practices and limitations

The Universal File Opener (UFO) and the AODocs File Opener (AFO) are browser extensions.

  • UFO is used in AODocs libraries using Google Drive. UFO is available in Google Chrome.
  • AFO in AODocs libraries using Google Cloud Storage or Azure Blob storage. AFO is available in Google Chrome and Microsoft Edge.

Learn more:

This article provides information and best practices for using UFO/AFO:

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General considerations

  • When you open a file locally, the download time depends on the size of the file and your internet bandwidth.
  • If you haven't already defined which software on your computer to use for a specific file type, a prompt appears asking you to select the appropriate software.
  • If you want to save a file in Acrobat Reader DC, you may have to select the destination folder. Learn more about using Adobe Acrobat Reader DC with UFO/AFO.
  • If you aren't allowed to copy, print or download a file, you can't download it and open it locally with UFO/AFO. An error message is displayed
  • If you have read-only access to a file, you can open it but you can only save it locally.

Note: The last point applies only to UFO. AFO doesn't currently support read-only access.

Restrictions on opening file types

The UFO/AFO button isn't available for files with these extensions:

.ahk  .bat  .cmd  .com .csh  .exe  .ksh  .lnk  .msc  .msi  .ps1  .py  .reg  .scr  .sh  

When you use the UFO button to open files with the following extensions, the message The file [filename] is an executable and will run a command when opened, do you want to continue? appears:

.action .ins .pif .shb .workflow
.app .isu .potm .shs .ws
.as .job .ppam .tlp .wsf
.command .jse .ppsm .u3p .wsh
.crt .msp .pptm .vb .xap
.docm .mst .prg .vbe .xlam
.dotm .osx .reg .vbs .xlm
.gem .otm .scr .vbscript .xltm
.inf .paf .sct .wiz  


Note: The message appears only if you're using UFO. AFO opens the files directly.

Important: This is not an exhaustive list. The message may appear for other types of executable files.

Using Adobe Acrobat Reader DC with UFO/AFO

When you save a PDF file after making changes, Adobe Acrobat Reader DC may prompt you to specify where you want to save the file. If the current folder of the file you are editing is not selected by default, you need to navigate and specify the location every time you save a document.

This is a default behavior of Adobe Acrobat Reader DC. It isn't related to UFO/AFO – you get the same prompt when you save a file locally without using UFO/AFO.

To be able to save files at their current location:

1. In Adobe Reader DC, select the menu Edit > Preferences (Windows) or Acrobat / Adobe Acrobat Reader > Preferences (macOS).

2. Go to the General section.

3. Disable Show online storage when saving files.


After disabling this setting, when you save files locally with UFO/AFO, they are saved at the current location and uploaded back to Google Drive immediately.

Note: Other PDF reading software, like Acrobat Reader Pro DC (paying) or Foxit Reader (free) don’t have this limitation. They save files to the current location without prompting you to select the location.

Editing files with external references

Some file formats, like Office formats (Excel external references) or AutoCAD (xref) allow you to set references to external files.

This use case is not currently supported by UFO/AFO, so you get errors if you try to open files that were created with external references.

Limitations with macOS

The following minor limitations may occur when you use UFO/AFO with macOS.


UFO/AFO notifications don't disappear and are duplicated

On macOs with Chrome 59, notifications don't disappear and are duplicated on your screen when you scroll down.

As a workaround, you can force Chrome to use the Chrome notification system instead of the macOS system.

1. Open a browser window and enter chrome://flags/

2. Scroll down to display the Enable native notifications flag.

3. Set the flag to disabled in the drop-down menu.


No UFO/AFO notifications are displayed

If you don't see any UFO/AFO notifications, make sure that your Chrome notifications aren't disabled.

1. Open your Mac System Preferences.

2. Select Notifications.

3. Make sure these checkboxes are selected:

  • Show notifications on lock screen
  • Show in Notification Center


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