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User agent results in 520 error response

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  • 16 views
  • Last reply by Georgergb

Georgergb
Georgergb
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Hi,

Someone is trying to visit our website but keeps getting a 520 error response.

It appears that their user agent is being blocked at some point but I don't know why or where (I have tested the user agent in browser tools and get the same response). Yet, using it to visit other websites works fine, likewise if they test using another user agent they can access the site.

We use Cloudflare but I don't think the issue is their end as we have sites hosted elsewhere which can be accessed through the CDN with the same user agent.

Checking the server logs shows no sign of the visitor's IP address accessing the site.

The user agent is: Mozilla/5.0 (Windows NT 6.1; rv:33.0) Gecko/20100101 Firefox/33.0

Just wondering if anyone can suggest how I might be able to narrow down where to find the issue or what I should be looking for? 33 seems like quite an old version, could it be the server doesn't accept visits from an older version?

Many thanks

Hi, Someone is trying to visit our website but keeps getting a 520 error response. It appears that their user agent is being blocked at some point but I don't know why or where (I have tested the user agent in browser tools and get the same response). Yet, using it to visit other websites works fine, likewise if they test using another user agent they can access the site. We use Cloudflare but I don't think the issue is their end as we have sites hosted elsewhere which can be accessed through the CDN with the same user agent. Checking the server logs shows no sign of the visitor's IP address accessing the site. The user agent is: Mozilla/5.0 (Windows NT 6.1; rv:33.0) Gecko/20100101 Firefox/33.0 Just wondering if anyone can suggest how I might be able to narrow down where to find the issue or what I should be looking for? 33 seems like quite an old version, could it be the server doesn't accept visits from an older version? Many thanks

Chosen solution

Hi

Firefox 33 was released in 2014 - it would be very much in their interest (both to access your website, but also for the security of their web browsing) if they updated to a more recent version.

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Georgergb
Georgergb Question owner
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Just an addition to my original post:

I have tested various versions of Firefox in Browserstack. Up to and including version 40 result in the 520 error message, versions 41 onwards are able to access the website.

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Paul
Paul
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Chosen Solution

Hi

Firefox 33 was released in 2014 - it would be very much in their interest (both to access your website, but also for the security of their web browsing) if they updated to a more recent version.

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Georgergb
Georgergb Question owner
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Thanks Paul.

Yes, ideally that would be the outcome. It's a web tool they are using which can access other sites but not ours. I have a feeling our hosting company must have stricter security rules that blocks older browsers.

I have tested various versions and it seems anything up to version 40 does not work, only later versions get access.

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