Arch Linux

peltlairphrasing

Member

Registered: 2025-10-25

Posts: 3

"Invalid username." when trying to sign into Proton VPN GUI client

Anytime I try to sign into the Proton VPN GUI client I always get the "Invalid username." error. The account credentials I'm entering are correct as I can sign in perfectly fine on a browser. This problem's exclusive to the GUI client. I reinstalled it but it did absolutely nothing. I emailed Proton about this and they said they don't support Arch Linux. So here's a post on the Arch Linux forums.

WorMzy

Administrator

From: Scotland

Registered: 2010-06-16

Posts: 13,111

Website

Re: "Invalid username." when trying to sign into Proton VPN GUI client

I don't use the gtk client, but I had a similar issue with the Android app. For me the solution was to manually type in my username+password, rather than copy+paste from somewhere else. YMMV.

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peltlairphrasing

Member

Registered: 2025-10-25

Posts: 3

Re: "Invalid username." when trying to sign into Proton VPN GUI client

I tried that method but it also didn't work. To test I logged out of the GTK client from a different machine and voila, "Invalid username". I also tried out a different account I have and still no dice on either machine.

Anon1234

Member

Registered: 2016-03-30

Posts: 8

Re: "Invalid username." when trying to sign into Proton VPN GUI client

I tried that method but it also didn't work. To test I logged out of the GTK client from a different machine and voila, "Invalid username". I also tried out a different account I have and still no dice on either machine.

Just wondering if you got anywhere with a solution. This happened to me about a week ago, same thing.

Things I have tried:
Downgraded to the last few cached versions
Uninstalled and reinstalled
Uninstalled and installed the flatpak version

and the same error.

Verified my credentials are correct, and can access the VPN on other devices (Non Linux)

Have temporally set up a config to use it as a Wireguard connection, which works, but I would like to have access to the app back again.

theorangeone

Member

From: ~

Registered: 2025-11-28

Posts: 1

Website

Re: "Invalid username." when trying to sign into Proton VPN GUI client

I hit the same issue. Did some digging, and found the cause of the problem. The error message is hiding a maximum password length constraint at 72 chars. If you reset your password to something with fewer than 72 characters, you can log in.

I had to modify the source to work this out, but I'm in now. I've raised it upstream to hopefully get it fixed: https://github.com/ProtonVPN/proton-vpn … issues/127

Anon1234

Member

Registered: 2016-03-30

Posts: 8

Re: "Invalid username." when trying to sign into Proton VPN GUI client

I hit the same issue. Did some digging, and found the cause of the problem. The error message is hiding a maximum password length constraint at 72 chars. If you reset your password to something with fewer than 72 characters, you can log in.

I had to modify the source to work this out, but I'm in now. I've raised it upstream to hopefully get it fixed: https://github.com/ProtonVPN/proton-vpn … issues/127

Thought I would add an update here.

I checked my password, and it was 64 characters long, so below the 72 you mentioned, however I had used all the security options (Upper and Lower case, Special Symbols, Numbers, ANSI characters,and special symbols) so I decided to change the password anyway, so something shorter and without the additional security symbols, and it worked!

So it could be the case that not only does it not like longer than 72, but it also has stopped liking the use of ANSI characters and special symbols. I had been using it for about 4 months fine, and then one day, it just stopped working. I will try to add on to your bug report on GitHub

Last edited by Anon1234 (2025-12-03 16:44:28)

peltlairphrasing

Member

Registered: 2025-10-25

Posts: 3

Re: "Invalid username." when trying to sign into Proton VPN GUI client

I gave up for some time on making it work, till today. Tried out a few theories I had to see if they worked and they did not. I did a search on the issue and recalled of this topic.

I hit the same issue. Did some digging, and found the cause of the problem. The error message is hiding a maximum password length constraint at 72 chars. If you reset your password to something with fewer than 72 characters, you can log in.

I had to modify the source to work this out, but I'm in now. I've raised it upstream to hopefully get it fixed: https://github.com/ProtonVPN/proton-vpn … issues/127

in my search I also found your Github issue. I changed my password to fit the requirement and successfully logged into the GTK client. They randomly changed this in an update, as previously my password that was much longer than 72 also worked.

Thought I would add an update here.

I checked my password, and it was 64 characters long, so below the 72 you mentioned, however I had used all the security options (Upper and Lower case, Special Symbols, Numbers, ANSI characters,and special symbols) so I decided to change the password anyway, so something shorter and without the additional security symbols, and it worked!

So it could be the case that not only does it not like longer than 72, but it also has stopped liking the use of ANSI characters and special symbols. I had been using it for about 4 months fine, and then one day, it just stopped working. I will try to add on to your bug report on GitHub

my previous password was randomly generated by my password manager and so is the new one. Both have upper, lower case letters, numbers and special characters. The newer one falls under the 72 character limit and works. Could be that you are on to something with them no longer allowing ANSI characters.