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If I test with links I get “Invalid certificate”. Something must be wrong. This is when I test from my workstation at home.
If I test it directly on the server with links, it connects without problem.
I have a problem with gajim chat-client. It refuses to upload an image with certificat_verify_failed. The autor of that client says it’s probably a problem with the local cert store. I already did a update-ca-certificates. 0 added, 0 removed; done. I don’t remember I had this problem before. I am using LinuxMint.
@JuergenAuer, I think you've misremembered this. I just did the test you suggested and I didn't see that message. Instead, I saw No client certificate CA names sent.
I believe unable to get local issuer certificate is a problem of a self-signed certificate or an incomplete chain (using cert.pem instead of fullchain.pem, for example). In a tiny number of cases, it could also be due to falling back to a default server certificate when neglecting to send SNI with the OpenSSL -servername option.