Web Programmer, "SecurityError: Access denied" on Linux (SOLVED)


Can’t connect with the web programmer, even though “DFU…” appears as a connection and I (try to) enable it. I get “SecurityError: Access denied”.

I’m on Chrome 65 on Debian.

Any ideas?

*edit: It seems I may need to add a udev rule for the device, for Chrome to have access to it, looking into that now

Hey, I solved this by adding a udev rule for the device in /etc/udev/rules.d, and it now works! For anyone else on Linux with a similar problem, this is what I did:

  1. You need the USB vendor and product ID of the device, for the seed it is “0483” and “df11”, respectively. It will be the same for you, but if you want to check, you can open a console and type lsusb | grep DFU, then look for the two numbers “ID xxxx:xxxx”.

  2. In a console type sudo nano /etc/udev/rules.d/50-daisy-stmicro-dfu.rules

  3. Enter the following: (no line break)

    SUBSYSTEM=="usb", ATTR{idVendor}=="0483", ATTR{idProduct}=="df11", MODE="0664", GROUP="plugdev"

  4. Ctrl+O, then Enter to save, Ctrl+X to exit nano. Disconnect / reconnect the seed, and press BOOT then RESET. You should now be able to connect with the web programmer.

Note: You may want to check that you are in the plugdev group (but you probably are), by typing groups


Thank you very much kborch !
It worked for me after some adjustments.
I’m on a Manjaro distro (ArchLinux family).
1- to find the IDs of the Daisy I typed lsusb -v
2- I changed the GROUP to one I’m already in
3- I had to reboot.
So glad it works on my linux laptop !
Cheers !

Hey Xavier, glad it worked for you too :slight_smile:

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Even after installing the usb rules and reboot, it didn’t work for me.
Chrome ‘snap’ version of Ubuntu doens’t allow usb access, see

sudo apt install chromium-browser

After that, it worked.

Hi all,
I cannot make this work - basically, chromium now only seems to install via snap.

sudo apt install chromium-browser

still installs the snap.

How do I install chromium-browser via apt?

How do I install chromium-browser via apt?

I don’t think you can, on Ubuntu. The Linux Mint devs – which have Ubuntu upstream from them – threw a shitfit about this (see here, for example https://blog.linuxmint.com/?p=3906).

In mint, I was able to manually install chrome using the .deb from google’s chrome website.
(Then got SecurityError when trying to access usb devices in the web programmer… had to do the udev rules fix documented previously in the thread, too.

Yes, I had this problem as well.

I assume you’ve already found a solution, but I’ll add this here as one possible solution (for those who don’t want to manually update a Chromium .deb all the time or set up an automation process for that…):

Easy Method: You can still install a Google Chrome .deb from Google Chrome - Download the Fast, Secure Browser from Google

(Funny Story: After adding udev rules, adding myself to the plugdev group, and restarting the system, I was able to flash ‘Blink’ on Snap Chrome before “They” knew what I was doing (I think) by opening Chrome immediately after login. Post flashing, the “connect” button was stuck on “disconnect” after Flashing (not correct behavior ). After the (Snap) rules loaded, the Daisy Seed was not allowed on Snap Chromium. This also was the result using Brave browser(chromium variant).

SO…if you must use Chromium, I saw this article How to Install Chromium as a DEB Package on Ubuntu 22.04
and Daisy likes it straight-away with a REAL (.deb) Chromium Beta version. If you’re comfortable with using this ppa (which is explained as having transparency, being posted on github (chromium-ubuntu-build/debian at master · saiarcot895/chromium-ubuntu-build · GitHub)

As an added bonus, this .deb browser is ORDERS of MAGNITUDE faster than Snap for uploading to MCUs.
Anyway, I’m just glad it works now.
Best of building to you.