I'm trying to vote up a good answer. But button does not working, then i open other some question for checking but these (Up Vote, Down Vote, Favorite star) are not working. Also this error is showing.
You should really consider switching to another ISP, because an ISP that introduces a Man-In-The-Middle attack is in fact hacking your connection and you shouldn't assume it's benign (original advice here).
Please note that there is an long standing and on-going effort to fully support secure connections over HTTPS/TLS across the Stack Exchange network that is riddled by both technical challenges and costs. See Accessing per-site metas gives 403 forbidden from cloudflare-nginx among other posts on the subject. Among the meta sites only MSE, MSO, MSU, MSF, and Meta Ask Ubuntu support TLS, yet all main sites are accessible through a secure connection.
Other things to consider:
- Make your browser disallow mixed content (with, e.g. NoScript and HTTPS Everywhere browser extensions).
- Force the browser to use TLS for all Stack Exchange and related sites (through NoScript settings, for instance), including sstatic.net, imgur.com, stackauth.com, gravatar.com etc.
- Fiddle with parameters until you see no mixed/dubious content is being loaded.
- Thoroughly check what Certificate Authorities your browser trusts.
- To securely access site metas other than those listed above, use either mobile apps, or Emacs with the SX extension.
This post is intentionally made community wiki since I have already posted practically the same answer over at M.SO.