If you are using the Mega file hosting service to host files and to download them, then you may have come upon a strange error message when you download large files from the service. Large files in this regard are files with a size of at least 50 Megabytes in size.

If you do, you will notice that the file download pauses after downloading for a bit, and that a notification is displayed on the screen that informs you of a problem:

Download Files Firefox needs your consent to download large files. Please click ALLOW to continue your transfer. If you cannot see the request, please click on the icon next to the address bar.

First, there is no allow in the notification which certainly confuses some users as they do not know what to do to correct the issue. A notification is displayed by Firefox that displays the allow button but it sometimes disappears after a short while (likely after user action on the page).

Here is what you need to do to sort this out.

Click on the first icon in the browser's address bar. Take a look at the screenshot to find out how it should look like. Clicking allow enables the Mega website to save more than 50 Megabytes of data on the computer. The download is resumed as soon as you select allow in the menu.

You are probably wondering why this message pops up at all, and why it is not popping up on other websites where you download files that are larger than a certain size. The size is set to 51200 Kilobyte by default

Mega apparently apparently delivers files using indexdb which requires permission if data larger than 50 Megabytes needs to be saved to the system.

Side note: The indexdb folder of your profile may grow quite large if you download files from Mega or any other website using the feature to your computer. What this means is that the file gets downloaded to the indexdb folder, and there the mega.co.nz folder, but also to another location you want to save it to. If you have downloaded some large files from Mega and wondered why your free disk space suddenly dropped to new lows, this may explain why.

Managing Permissions

You can manage the permissions for each website in Firefox in the following way.

Load about:permissions in the browser. You can filter for a specific website here, for instance mega so that only it is displayed. Now you can modify all default permissions, so that you allow or disallow the website to make use of them. You need to set the Maintain offline storage permission to allow for the site in question so that it does not run into the 50 Megabyte download size limitation anymore.

Clear the offline data

You have two options to clear the offline data. You can open the Firefox profile folder and delete all sites or only a specific site in the indexdb folder of the browser, or use the interface of the browser to clear some or all offline data.

Option 1

Press the Alt-key and select Help > Troubleshooting Information. Or, load about:support directly in the browser's address bar. Click on the show folder here next to profile folder to open the root profile folder. Click on indexdb here to open that folder. Here you find the urls of all websites that have used the feature to store data on your system. Delete the folders of sites here to clear the storage on your hard drive.

Note: Mozilla has changed the folder the files are stored in from Firefox 26 onwards it seems. You now find the folder under storage/persistent/ in the Firefox root profile folder.

Option 2

Press the Alt-key to display the menu bar and select Tools > Options. Switch to Advanced > Network. Press the Clear Now button to clear all data at once.

Closing Words

This tip is especially useful for Firefox users who have installed the browser on a Solid State Drive as space is usually scarce. So, if your space is running low this may be one of the locations to check out.

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