Andrew Spencer

Uwe, I tried this immediately on seeing your post, and it worked (once). But then it stopped working. In the past few hours, with reboots and various other attempts at fixes, it has somehow worked, but again only once. Closer, but it is not (yet) the solution. In WireShark I do now see that TLS 1.3 is now being used in the transactions, but the 12175 error persists. I have been trying things on two separate PCs - one with Delphi 11.1 / Windows 10 and the other with Delphi 10.4.2 / Windows 10

Does anyone have advice on an alternative for the TRESTClient / TRESTRequest / TRESTResponse set of Embarcadero components? I have found that the ICS TSslHttpRest component does work (and uses TLS1.3), but the lack of documentation and sample code, and the odd handling of JSON mean that committing to replace all Embarcadero TRESTxxxxx operations in my code may be overly risky. The best would be a well-supported, documented (commercial) solution (or a component fix from Embarcadero!) Rolling back the Windows update is not going to be a good solution for large corporate clients spread all around the world!

I have tried to use the SecureProtocols property of TRESTClient, but it makes no difference. (In the large application that had been working fine till KB5018410 came around, I used the default, which is none of these protocols ticked) I have also tried various options (with rebooting) in the Control Panel -> Internet Options -> Advanced -> Security -> Use TLS x.x It did not change anything. I agree with Brian Evans' comment, above " No combination of settings gets it to work again on a patched Windows 10 system (KB5018410). There is some weird interaction between the patch and Delphi REST components it seems. It breaks TLS 1.2 somehow and TLS 1.3 isn't functional either." A WireShark capture, trying to access our site, shows TLS1.2 attempts, but results in a 12175 in the Delphi Application Insomnia, by contrast moves to TLS1.3 My application is attached. SimpleREST.zip

Hi Brian I agree with what you have found. I am running Delphi 11.2 patch 1 and Windows 10. This problem has also been seen under Delphi 10.4.2. As with your tests, I get no operations with any variation of the Internet Properties "Use TLS x.y" checkboxes. It sounds as if this should be raised on the Delphi bug website

AFAIK: Your URL should specify "https:/xxxxxxx", if so required. Or a forwarder on the server side will route to https Parameters and values are input as part of the TRESTRequest.Resource parameter. These are added to the Base URL, which is in TRESTCleint.BaseURL

It seems to me, after some sniffing with WireShark, that TLS1.2 is not available following the KB5018410 roll-out. TLS1.3 protocols are being used by Insomnia, Firefox etc requests. The Delphi TRESTClient/TRESTRequest/TRESTResponse suite, however, seems to be stuck on TLS1.2. I have tried setting SecureProtocols parameters in TRESTClient (which are unchecked by default), but this has made no difference. I made a quick change of my simple application to use the ICS TSslHttpRest component. Not having used it before and hardly knowing how to use it, I could quickly see that it is reaching our server and polling the above URL correctly. However, it is definitely not going to be viable/quick to change our application's usage of the TRESTxxxxxx components to the ICS component. It seems to me that the TRESTClient (?) component is not performing correctly. I've attached my test project SimpleREST.zip