The error messages that you're getting when attaching files.
   If you've tried using other browsers when you've experienced your concern.
   The last activities performed on your device prior to your concern.

   Locate and click the three horizontal bars at the top right portion of the browser.
   Image
   Locate and click on the Advanced menu.
   Locate and click on the Update tab.
   Under Firefox updates, locate and click Show Update History.

   If you're using a device that is managed by a domain or an organization.
   If you've tried accessing the specified mail system on another device.

Q: Can't attach file in Outlook Web App You are subscribed to this thread I was unable to attach files in Outlook Web App. I using Edge on Win10 but for this particular reason, switched over to FireFox. That worked like a charm. For a month. Then stopped. Today. I checked and it allows pop-ups for the site. Not sure what else to do. I had to switch over to Gmail to send the attachment. Suggestions on things I can check? I'm posting this under outlook.com as I don't see any more appropriate option. Replies (8) Jelu Cal Jelu Cal replied on Microsoft Hi Jim, Your concern about attaching files when sending emails via Outlook Web App (OWA) can be due to the configuration of the browser that you're using. To better understand your concern, we'd like to know the following: The error messages that you're getting when attaching files. If you've tried using other browsers when you've experienced your concern. The last activities performed on your device prior to your concern. To determine if this was caused by an update on the specified browser, you can perform the following: Locate and click the three horizontal bars at the top right portion of the browser. Image Locate and click on the Advanced menu. Locate and click on the Update tab. Under Firefox updates, locate and click Show Update History. In addition, we'd recommend checking with Internet Explorer and see if you'll be able to attach the specified files. Performing this will help us isolate browser specific issues. We look forward to your response. Did this resolve your issue? JP Jim P. Stewart replied on I have several browsers installed, tried them all. Here are the results: -Firefox. When I click on the 'attach' button, there is no error code. Literally, nothing happens, nothing at all as if I never clicked on it. There WAS a security update a couple of days ago when I look at the history so maybe that's it. As mentioned, Firefox was working flawlessly till yesterday. The update history says: Firefox 56.0 (20170926190823) installed on 10/5. -Edge. Same thing. When I click on 'attach,' nothing happens. Microsoft Edge 40.15063.0.0 -Chrome. Same thing. No response. Version 61.0.3163.100 (Official Build) (64-bit) -Internet Explorer. This is the only browser that works and allows me to attach files. But it has one other issue that makes it difficult to use. (I am running Win 10.) I am unable, whether using a private or public connection, to unclick the 'Use the Light Version' button. So the mail has a horrible interface and I'd just as soon be able to use any of the other three. Is it even compatible? My guess is not. IE version 11.608.15063.0 Image - Did this resolve your issue? Jelu Cal Jelu Cal replied on Microsoft We appreciate your response. An OWA mail system is being managed by the host. Features and functionalities can be set by the administrator based on the security structure of an organization. We'd like to know the following to further isolate your concern: If you're using a device that is managed by a domain or an organization. If you've tried accessing the specified mail system on another device. In the meantime, we'd recommend performing the steps posted under the How do I get to the standard version of Outlook Web App? section of this link to switch your version. This will be an alternative way of turning off the light version. In addition, you can download an older version of your preferred browser to remove the latest installed update. We'd recommend checking the process in the support website of your preferred browser. We look forward to an update on your concern. Did this resolve your issue? JP Jim P. Stewart replied on Please leave this open for a bit. There's a fair investment of time in doing the things you suggest and I can't get to it right away. Did this resolve your issue? Jelu Cal Jelu Cal replied on Microsoft You can update this thread to let us know of any developments related to your concern. We look forward to an update on your concern. Did this resolve your issue? JP Jim P. Stewart replied on I've decided to close this one as whatever the reason that I can't attach files, it's too much trouble to track down. I'll just continue doing what I have been doing which is when I have to attach files, use gmail. I'll let the company I'm working for figure it out. Did this resolve your issue? DA dannymulligan replied on I am having the exact problem as Jim and it started at approx the same time. I can only attach files by using the light version of Outlook web app. The update that may be responsible is: Users of 32-bit Firefox on 64-bit Windows are migrated to 64-bit Firefox for increased stability and security. DA dannymulligan replied on In response to the questions by Jelu Cal above: I work remotely by loging on to my employers web app I have logged on using a different computer and have the same problem Is this issue being caused by Microsoft or by Firefox? Question Info Views: 67 Last updated: October 13, 2017 Applies to: Outlook.com / Email / Sending and receiving attachments