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Problem with OpenSSL 1.1 after Qt update?



  • Hi,

    I recently updated Qt from version 5.10 to 5.15 (on windows 10 writing applications for windows 7 to 10). During the update something went wrong and I had to uninstall the entire environment and reinstall it from scratch. It took me some time to get everything back up and running, but when I was finally done and started testing that my application worked i noticed that something was wrong with my network communications.
    After some trial and error I realised that if I used my connections with just http things worked fine but with https I just got error 99 (Unknown Network Error) any time I tried to fetch information on the server. After som googling I found out that in Qt 5.12 a switch was made to OpenSSL 1.1 and that it's incompatible with OpenSSL1.0. Could this be the reason I'm having these issues? If so, how can I make my application compatible with OpenSSL 1.1, or is there a way to switch back to OpenSSL 1.0 to test and see if this is the issue? I've tried using the Maintenance Tool, but the only OpenSSL version available through there is 1.1.1.

    Any ideas?


  • Moderators

    @DanBar said in Problem with OpenSSL 1.1 after Qt update?:

    If so, how can I make my application compatible with OpenSSL 1.1

    It should be enough to just link to it during build and then make sure proper DLL files are in the same directory where your .exe is built. Which DLLs you need and what file names they are depends on compiler used and Open SSL version - sorry I don't remember them exactly, I use Windows only sporadically. If I recall correctly there used to be 2 DLLs in old versions, but nowadays it's a single file and it's called something like libssl-1_1-x64.dll.

    or is there a way to switch back to OpenSSL 1.0 to test and see if this is the issue?

    OpenSSL 1.0 has reached end of life a long time ago. DO NOT USE IT, it is a serious security risk at this point.