I’m having this same issue. Previously received some direction from your support team about this with no success. Here is our prior correspondence…
“I’ve been having an issue attaching files for some time now. It started all of a sudden a couple months ago and still persists. Every time I attach a file from my computer, it fails and I receive the message, “Failed to attach (filename)”. See attached for example. This happens every time I try to attach a file. However, it will almost always let me attach if I try a second or third time, but I have to let it fail the first time and try again. I’ve reviewed other Help discussions in your forum for answers but nothing I’ve found has resolved my issue. Any idea why this suddenly started happening and what I can do to fix it?”
"Thanks for writing in, I’m sorry to hear that you’ve run into trouble here!
I suspect that this could be caused by a browser issue. I can certainly understand how frustrating this can be, but the good news is that these issues are generally fairly quick to resolve.
If you don’t mind, please take a moment to try the troubleshooting tricks I’ve listed below. One of these is likely to resolve the issue, but at the very least it’ll give me an idea of where to look for the source of the problem:
• Test Asana on another supported browser. If it works in Firefox but not in Chrome, for example, this indicates that the problem may be with Chrome, and one of the steps below may help fix it: https://asana.com/guide/help/faq/connectivity#gl-browsers
• Disable browser extensions while using Asana. You can test this by using an incognito or private browsing window. This disables browser extensions by default. If it works in Incognito/private mode, you may need to try switching off some of your extensions to see if any are causing conflicts with Asana: https://asana.com/guide/help/faq/connectivity#gl-troubleshooting
• Update your browser to the latest version.
• Clear your browser’s cache.
If you’ve already tried some of these, please still try the others. If your issue is not resolved, please don’t hesitate to let me know and I’ll be happy to dig into this further."
"I tried it in Chrome, fully updated, temp files cleared, browser settings reset, and browser restarted. Also tried it in incognito mode.
I tried it in Internet Explorer 11, temp files cleared, browser settings reset, and browser restarted.
I tried it in Microsoft Edge, temp files cleared, browser settings reset, and browser restarted.
Experienced the exact same results in each browser and every circumstance. Every time I try to attach/upload a file from my computer it fails on the first attempt after a couple minutes. But if I wait for it to fail and then go through the same steps again to upload the same file, it will quickly upload the second time. Sometimes I will have to try a third time, but it’s very rare. Another scenario is, I select more than one file to upload; the first file will fail after a few minutes and the second one will immediately upload successfully and quickly. This started happening a few weeks ago and has been doing it ever since. I’ve even replaced my computer since it started; problem did not go away."
(no further response from Support at this time)
I’ve now followed some of the steps you’ve described here, and here are the results…
Any help you can give would be greatly appreciated as this is a very annoying issue.