Hi Ron, I'm not sure I understand attaching a document to an email through a SharePoint site. Does that mean the file you want to attach is not on your computer? If it's not on your computer, how do you select it for uploading?

Does it matter what type of file you're trying to upload (DOCX, XLSX, PDF, image)? For example, some types work okay and some trigger that error?

Some types of files cannot be uploaded but others can:

Sometimes the settings file that stores download handling preferences becomes corrupted with inappropriate file associations that cause uploading problems. You can rename the file and have Firefox rebuild it. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > Exit/Quit
• (menu bar) File > Exit (or Firefox > Quit)

Pause while Firefox finishes its cleanup, then rename handlers.json to something like handlersOLD.json. If you see a file named mimeTypes.rdf, it's obsolete, you can delete it.

Start Firefox back up again. Any improvement?

Hi JScher2000:

Nope, this did not correct my issue. Basically SharePoint is just pointing to outlook.office.com where it launches Outlook. It's nothing more than OWA and I could test it while connecting without going through SharePoint.

I removed the mimeTypes.rdf and also renamed the handlers.json to handlersold.json, but that did not correct the issue. Although it took longer to come back and tell me that it files could not be attached.

The files are local on the PC that I am testing with. I've tried with xls, xlsm, docx, txt files and more. Unfortunately, none of them work. I also do not believe that size is a matter here. I've tried with files as little as 12kb and as big as 189kb. I could try files >1mb if you'd like.

Thank you, Ron

Hi Ron, you're on Office 365, so it should be the most modern version of Exchange Server. I haven't heard of problems attaching files there, but things do change from time to time.

"Try again later" is a very strange error message. It implies that there's an issue on their side rather than on yours. But why would there be an issue?

Thank you for testing in Firefox's Safe Mode. There are a couple more routine things we suggest when a site generally known to work in Firefox stops working normally:

Double-check Firefox's Content Blocking: Firefox's Content Blocking feature may break websites that use third party components or require third party cookies. (In Firefox, "third party" means a different server name, even if it's a Microsoft server.)

Do you see a shield icon toward the left end of the address bar, near the lock icon? More info on managing the feature in this article: What happened to Tracking Protection?.

Cache and Cookies: When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "Clear Cookies and Site Data"
• (menu bar) Tools > Page Info > Security > "Clear Cookies and Site Data"
• click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "Clear Cookies and Site Data" button

In the dialog that opens, you will see one or more matches to the current address so you can remove the site's cookies individually without affecting other sites.

Then try reloading the page and logging in again. Does that help?

I checked the content blocking and it's set to Block all detected trackers but only in private windows. It's also set to for Trackers only under Third Party cookies.

I thought I had cleared the cookies and site data originally, but I did it again and this time it seems to have corrected my issue.

I tested it after clearing the site data and I received 2 files from the computer. The desktop.ini file and an excel file.

I believe I'm all set.

Thank you very much for your help.

Regards, Ron