0

I have C# WPF net framework 4.7.2 app running which has been working for about 18 months on 1200 computers.

Just this morning I have had support calls as a number of computers cannot load our app.

In debug we are finding that RestSharp is having issues getting a secure channel:

The request was aborted: Could not create SSL/TLS secure channel. no expection data

After more research I've found that the computers seemingly affected are all WINDOWS 7 computers.

I have this in my restsharp code:

 ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

(just in case someone was going to mention it)

The issues just started a few days ago but I cant seem to find the solution.

When the user loads our website it works fine, so it seems to be related to either RestSharp or perhaps a net framework update??

Can anyone please advise of how I can fix this or diagnose further as I'm a startup and really can't have these systems offline right now.

I do appreicate Windows 7 is OLD but this has been working for 18 months so my clients won't accept me saying "get a new comp" as the answer.

Thanks very much for any advice.

Improve this question

2 Answers 2

Reset to default
0

Can your clients run something with admin privileges? If so, try this PS script to enable TLS 1.2:

New-Item 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server' -Force
New-Item 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client' -Force
New-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server' -name 'Enabled' -value '1' –PropertyType 'DWORD'
New-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server' -name 'DisabledByDefault' -value '0' –PropertyType 'DWORD'
New-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client' -name 'Enabled' -value '1' –PropertyType 'DWORD'
New-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client' -name 'DisabledByDefault' -value '0' –PropertyType 'DWORD'
Write-Host 'Enabling TLSv1.2'

This worked for me. MS is making it harder to use W7 (obviously they want you to upgrade).

Improve this answer
Sign up to request clarification or add additional context in comments.

4 Comments

Thanks Jim. Did you just get this issue too?? I've got no idea why this suddently happend. Yes i can run as admin so ill try this out tomorrow.
Ive tried this, ive even tried this stuff: bonguides.com/how-to-enable-tls-version-1-2-on-windows-7 But i can't seem to get it working. At the moment I'm just trying to get a successful connection using powershell so i can limit it to a windows connection but even PS isnt connecting correctly. Apparently it might be a Cipher issue. but no idea why it suddenly started.
I forget the exact history on this, but I think some Windows update may have caused the problem. I had to deal with this a few months ago on one on my own machines, and the PS I posted fixed it.
Thanks Jim, looks like this hasnt fixed for me as I was enforcing the TLS in my code already. My issue seems to stem from the ciphers being used not being accepted by my server.
0

I FIXED IT!!

In WHM SSL/TLS configuration: Fault SSL/TLS type, RSA was still selected because CPANEL apparenrly auto ships with that as default.

I have no idea why everyhting suddenly changed, but i achanged to RCDSA P256 and refreshed the SSL and now I'm still A+ on the SSL checker site but windows 7 works fine again!!WHM

Improve this answer

Comments

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.