Twitter / X's t.co is somehow blocked. What is blocking it?

[LL0rd]

Hi everyone,

I'm experiencing a problem with Vivaldi on my system, specifically when trying to access links using Twitter/X's t.co redirect/tracking domain. For some reason, these links are getting blocked, and I can't figure out why.

When I try to open a t.co link, I get an ERR_ADDRESS_INVALID error. However:

• I can ping t.co successfully.
• Using curl, I get the expected 301 redirect.
• The same link opens perfectly in Firefox.

In Vivaldi, I’ve already tried to unblock it. On the error message page, I clicked the shield icon next to the URL and selected "Don't block anything" (my browser is in German, so this might be phrased slightly differently). Unfortunately, this didn’t resolve the issue.

Has anyone else encountered this or knows how to fix it? I’d really appreciate any advice. Thanks in advance!

[mib2berlin]

@LL0rd
Hi, I guess we need the link from Twitter/X to test this, open t.co work fine.

[OliJen]

@mib2berlin Have the same issue, every time.

Try this one: https://t.co/vCwuetSCBK

[mib2berlin]

@OliJen
Hi, does this link really link to YT?
No issues with the internal ad blocker, without or with uBlock Origin Lite:

[DoctorG]

@LL0rd Could be many culprits:

• Secure DNS setting
• Browser policy management
• GeoBlocking by provider
• VPN
• Proxy
• Company firewall
• Router filter
• Parental Control software
• Security software

[LL0rd]

@DoctorG said in Twitter / X's t.co is somehow blocked. What is blocking it?:

@LL0rd Could be many culprits:

And how to find THE reason for this issue?

• Secure DNS setting

My OS is Windows. As I mentioned, I can resolve the Domain with nslookup and other browsers can resolve the DNS and open the Page, so this can't be the reason. Or Vivaldi has it's own DNS Settings some where. But I havn't touched them after installation.

• Browser policy management

It's the default browser Installation. So I have no Idea about any kind of policies.

• GeoBlocking by provider

Same as your first Idea. If it's working with another browser, it can't be any kind of geo-blocking

• VPN

No VPN

• Proxy

No Proxy

• Company firewall

No company, but there is my own firewall. But if another browser can resolve and open the URL, why not Vivaldi?

• Router filter

same as firewall.

• Parental Control software

Nope

• Security software

No Security Software, besides Windows Defender. And there is no rule about blocking the t.co Domain or any traffic by Vivaldi.

[DoctorG]

@LL0rd Try Guest Profile and tell if that works.
If yes, some extension or Vivaldi Blocker rule block in your regular profile.

Or broken extension settings, remove and re-add extension helps in rare case.
And can try to reinstall Vivaldi 7.0 Stable (will not lose any profile data).

[mib2berlin]

@LL0rd
You cant compare with Firefox, best is to test with Chromium or at least a Chromium browser.
A guest profile is a good start point.

[OliJen]

@mib2berlin I checked on mobile, in another browser - no problem. It was a link integrated in a Community Note on X - and when I click it on Desktop, it gives me this error:

[DoctorG]

@OliJen Could be destination page after redirect is unreachable.

[mib2berlin]

@OliJen
I still can reach the page, can I may ask where you are located?
I can test this with my VPN service.

[OliJen]

@mib2berlin Of cause. Copenhagen, Denmark. FYI, I have the latest Vivaldi update.

[DoctorG]

@OliJen Can you open in Vivaldi chrome://net-internals/#dns and click "clear host cache"? And then check DNS lookup on the internal page for t.co?

[LL0rd]

@OliJen One Question, do you have WSL installed and enabled on your machine?

Just now, I saw this "effect", that honestly I can't explain.

Firefox works fine.
Brave - same error as Vivaldi (also Chrome Based)

Then I tried nslookup and the address was resolved. But when I tried to ping t.co, ping wasn't able to resolve the hostname.

C:\Users\dr>nslookup t.co
Server:  UnKnown
Address:  10.111.222.1

Nicht autorisierende Antwort:
Name:    t.co
Address:  172.66.0.227


C:\Users\dr>ping t.co
Ping-Anforderung konnte Host "t.co" nicht finden. Überprüfen Sie den Namen, und versuchen Sie es erneut.

Because I had WSL installed on my system, all I did was to start WSL and ping t.co. And it could be resolved. Then I tried it with the regular cmd CLI and:

C:\Users\dr>ping t.co

Ping wird ausgeführt für t.co [172.66.0.227] mit 32 Bytes Daten:
Antwort von 172.66.0.227: Bytes=32 Zeit=10ms TTL=58
Antwort von 172.66.0.227: Bytes=32 Zeit=9ms TTL=58

It's working. I think, there is some kind of DNS hickup on Windows with WSL. Because the only thing I did was to start WSL. That's it.

[mib2berlin]

@OliJen
OK, this is not a localisation issue, logged in to Copenhagen.

[OliJen]

@LL0rd It does not appear so.

[shojivrstrinova8]

how about vivaldi adblocker?

[DoctorG]

@shojivrstrinova8 Vivaldi Blocker does not block X by default.
And in Vivaldi Blocker no list (i checked all!) do block the t.co redirects.

[DoctorG]

@LL0rd Had you checked firewall?
https://github.com/microsoft/WSL/issues/4171

And could be trouble with routing of IPv4 and IPv6.