Can't attach files with Safari in Gmail.

Hi TonyFadd, 

You mentioned "I've updated my Safari browser" in your first message, does that mean you updated your macOS or updated Safari a different way? You also mentioned that you've tried all the steps in If Safari on Mac doesn't open a webpage or isn’t working as expected - Apple Support, but there is one we wanted to follow up on.

Install software updates

Install all available Apple software updates, which can include updates for Safari.

If the issue continues, let the community know the exact version of macOS you're currently running and what happens when you try to drag and drop the file from your computer to the email message.

We hope that helps with your question and take care!

Hi TonyFadd,

Welcome to Apple Support Communities. It sounds like you are composing an email from Gmail webmail in Safari when this happens. Right?

Do you have the same issue if you add an attachment to an email in the Mail app? Guidance below is from Add attachments to emails in Mail on Mac - Apple Support

"Include photos and other files in emails

In the Mail app on your Mac, do any of the following in a message you’re writing:

• Click the Attachment button  in the toolbar, locate a file, select it, then click Choose File.
• You can also drag files from the desktop, the Finder, or an app into your message.
• For photos, click the Photo Browser button  in the toolbar, then drag a photo into your message. You can also take a photo or scan documents, or add a sketch, using your nearby iPhone or iPad.
• To forward an email as an attachment, select the message, then choose Message > Forward as Attachment. Or drag a message from the message list into the message you’re writing."

If this only happens in Safari, try all sections and steps from If Safari on Mac doesn't open a webpage or isn’t working as expected - Apple Support which can help with issues with individual websites.

Take care.