Local flash can't load in browsers

 Answer:

You may have met the problem when you load flash files locally in browsers, for example open offline webpage with flash content. The flash plugin was loaded successfully but display nothing. How does it happen?

Searching from release notes of Adobe Flash Player, I found a new feature in Flash Player 23 - Disabling local-with-filesystem access in Flash Player by default, please refer to https://helpx.adobe.com/flash-player/release-note/fp_23_air_23_release_notes.html.

Evidently this is the reason why local flash can't load in browsers. Adobe made this change to keep flash player accord with modern web security, while for users who require this function, the legacy behavior can be restored as follows.

———————————————For Windows—————————————————

For Individuals:
For Internet Explorer, Edge, Firefox, Opera and Safari:
On the affected system, go to: Control Panel > Flash Player > Advanced > Developer Tools > Trusted Location Settings
Click the icon and add relevant flash files, folders or disk drivers to the list.

For Google Chrome (and similar PPAPI browsers):
Navigate to the settings manager page
Choose Edit Locations > Add Locations from the list.

For System Administrators:
The legacy behavior can be restored by the following steps.

Find mms.cfg in flash player installation directory.

For 32bit Windows C:\Windows\System32\Macromed\Flash\mms.cfg

For 64bit Windows C:\Windows\System32\Macromed\Flash\mms.cfg and C:\Windows\SysWOW64\Macromed\Flash\mms.cfg

Open mms.cfg with text editor and add EnableInsecureLocalWithFileSystem=1 flag to it, save and close editor. Note that both files in 64bit Windows need to do this modification. If you can't find mms.cfg in those directories, right click to new one.

—————————————————For Mac—————————————————

Go to: System Preference > Flash Player > Advanced > Developer Tools > Trusted Location Settings

Click "+" to add relevant flash files, folders or disk drivers to the list.

Usually /Application and /Users are suggested to add in to the list.