Double-clicking HTML, PDF, or ePub files fails to open with default app until 'Hide extension' is checked

Question

Double-clicking HTML, PDF, or ePub files fails to open with default app until 'Hide extension' is checked

I generate HTML, PDF, ePub files using AsciiDoctor workflows.

Today, for the first time, several files that I generated were not opening when I double clicked on them.

I attempted to research why this happened, could not find any other answer than to associate the file with an application. But the Finder would not allow me to do that.

I opened the file with Get Info from the Finder.

I clicked on the checkbox in the "Name and Extension:" heading labeled "Hide extension".

When I did that the file moved to the bottom of the Finder list, with was sorted by "Date Modified." which applied the current time to the file.

Now the file could be opened by the finder with the default application.

Does anyone know why HTML, PDF, and ePub files could not find their default applications when double clicked?

Why are standard file types not capable of being set in GetInfo?

Why does 'Hide extension' change the file to behaving normally?

[Edited by Moderator]

Original Title: Sonoma When opening HTML, pdf, or ePub file with default app does not work, using Hide Extension helps

MacBook Pro (M3 Max, 2023)

Posted on Aug 5, 2025 9:30 AM

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Answer 1

VikingOSX

Level 10

122,628 points

Aug 5, 2025 10:20 AM in response to The White Rabbit

In macOS, not just Sonoma, the default opening applications on double-click for certain file types are as follows:

HTML - Apple Safari
PDF - Apple Preview
EPUB - Apple Books

unless you change the default browser in System Settings > Desktop & Dock > Default web browser. To change the default application for PDF or EPUB, you single-click on any one of these files and press opt+cmd+i to open the Get Info panel. In its Open with section, you select the default application you want, and then click through the Change All… button.

Hiding the file extension does nothing as the operating system still sees it and knows which application is currently the default to open that file. The operating system maintains a database of file extensions and the applications that governs the default, as well as the alternative applications that can open those files. Do not change any file extensions or nothing may open them.

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