So, ran into this one. Firefox is throwing this error, along with ‘SSL_ERROR_RX_RECORD_TOO_LONG’. Turns out, apache was serving plain HTTP on port 443, as it hadn’t been given a default SSL config.

Other causes may be: Corrupted SSL cert (rare). Mis-configured proxy. Not adding “SSLEngine On” after configuring an SSL cert. But mostly, you’re trying to talk HTTPS to an HTTP serving webserver.

`a2ensite default-ssl` (on debian) fixed it. Well, fixed in in that the default server now has a snake-oil self-signed cert, but, you know, fixed it. 🙂

If you get these errors:

W: Possible missing firmware /lib/firmware/rtl_nic/rtl8105e-1.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168e-2.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168e-1.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168d-2.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168d-1.fw for module r8169

or

W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168f-2.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168f-1.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8105e-1.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168e-3.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168e-2.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168e-1.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168d-2.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168d-1.fw for module r8169

Do this as root (or using sudo):

#  apt-get install firmware-realtek

Win!

If you have other firmware issues, n1md4 suggested installing: firmware-linux and firmware-linux-nonfree in the comments (thanks!)