Technic Launcher fails to download modpack from https: Web site

[amysoxcolo]

I recently set up my personal Web site, which contains my Minecraft modpack zip file, to use HTTPS with security certificates from Let's Encrypt, and to automatically redirect all http: URLs to https:. One of my players reported he could not download my modpack with the Technic Launcher. I fixed the URL configured for the modpack on the technicpack.net site to start with https: rather than http:, but he still reported problems. I later duplicated this issue; the log file is attached as bug.log.txt. The error it throws is a "javax.net.ssl.SSLHandshakeException: Received fatal alert: handshake_failure".

Environment: Technic Launcher 4.347, Java 1.7.0_80 on Ubuntu 12.04 LTS 64-bit.
Steps to reproduce:

• Set up a modpack that downloads its contents from an https: URL. The certificate for that site should be supplied by Let's Encrypt.
• Attempt to install that modpack with Technic Launcher.

Expected behavior: The modpack installs.
Actual behavior: An error dialog pops up saying that the .zip file could not be downloaded. The logged error messages are as given in the attached logfile.

(I worked around the problem by configuring an alternate domain name that is not secured with which to access the modpack .zip file.)

[cadyyan]

I am also having this issue. It stems from Java not supporting the Let's Encrypt CA cert. I'm trying to install the necessary certs but haven't had much luck yet.

[Crazylom]

For some reason, my problem was solved with changing hosts entries.
Apparently, there was one including dropbox domain (which was displayed on error window when modpacks failed to download).
After deleting it and writing classic 127.0.0.1 localhost, everything started to work.

File is located in Windows/system32/drivers/etc, but is hidden as system secured file.
press alt while in windows explorer,
"Service" in downdrop list above,
"instruments" or "folders properties" i dunno,
"view",
turn "hide protected OS files" checkmark off.

Enjoy seeing and editing the forbidden.