I'm cross-posting this answer here in case anyone else comes across this thread in the future:

In concrete5.4.2.2 and earlier, go to Dashboard > File Manager and click the Access tab at the top, you'll see a box named Allowed File Types.

In concrete5.5 and above, simple enter "Allowed File Types" into the Dashboard's Inelligent Search field (or go to Dashboard > System & Settings > Permissions & Access > Allowed File Types).

This field is supposed to contain a list of all the types of files you're allowed to upload, but if you're experiencing this problem, this field is likely blank. Even though the admin is technically allowed to upload files, no file types are allowed...so the file upload buttons disappear.

To fix this, paste the following into the Allowed File Types field and click Save:



UPDATE 2/15/2012:

This is not caused by one-click installer services as previously suspected. We've figured out that the culprit is likely the HTML5 Music and / or HTML5 Video add-ons from the Marketplace. These add-ons inadvertently wiped out the missing Allowed File Types values upon installation. The add-on developer has been notified and asked to fix this bug. Please see this thread for more info (note that while it's in the Bug Tracker for concrete5.5.1 it is NOT actually a core bug):

http://www.concrete5.org/developers/bugs/5-5-1/upload-file-options-...

Re-adding the Allowed File Types in the method specified above should work as reported. Alternatively, there's an SQL query you can run to fix this, noted in the link posted above.

Hope this helps everyone!

THANK YOU!! I did an update yesterday and noticed this morning that the browse/upload buttons in File Manager were missing. Your fix worked great and I'm back up and running. By the way, our site is hosted on BlueHost. I don't know why that would be an issue, but noticed that you were referencing it as a possible cause.

Thanks,
Rich

Kind of strange... I have not done an update for weeks and I have been uploading files for the last week or so, and even earlier today, and all of a sudden, all my upload buttons were gone. At first I thought I was looking in the wrong place for them, then, and not finding them I thought I was losing my mind. I even went to a separate C5 site that I am an administrator on to make sure they were where I thought they were. As you suggested they were gone. So I copied them from the one site to the other as you suggested and I was back up and running. Funny thing is that my concrete5 site/s are also hosted on BlueHost. this did not happen to both sites at the same time, but both sites mentioned are hosted on one user account at Blue Host.
Thanks again for the help. Your post got me up and running in less than five minutes from discovering the issue.
Albin

I updated recently to version 5.5+ and encountered the same problem.
following the previous version path didn't work (obviously: there is no access tab)

to fix the problem in the latest version:
click on dashboard | systems & settings | and in the right column, middle section you will find the link to the "allowed filetypes".

when you click it, it will open and you will notice it is empty. Add the missing filetypes (shown in first reply) and you are good to go.

Just curious is your host BlueHost?

Hi,
No, i'm using namecheap.
i'm pretty sure it's not a provider issue.
although it is possible that it has something to do with the way caching works and how the upgrade functions.

i have upgraded my site a few days ago. So it would be strange that suddenly only one site of me has this problem, while i have another one running there in a subfolder.

from all the providers i have used (godaddy.com, bluehost.com, namecheap.com argeweb.nl and 1eurohosting.nl) i only had serious problems with godaddy. I got it all running but it was slow as hell.
bluehost was fair, namecheap is cheap and works pretty well. The fastest i found so far is 1eurohosting. (wherehttp://www.c5cms.nl is a showcase)

Paul

Thanks for your reply.

Albin

Hi folks,

We believe we've found the cause of this. Please see my updated post above.

cool