Warning: url link is unreachable after change my domain name

Warning: url link is unreachable.

That message will usually show for the first few days on a new website. That happens whether it's a brand new domain or simply one that hasn't had Facebook integration before. The message should go away automatically after Facebook has scanned some of your pages, which it will automatically do over a short period of time.

However, on that site, there may be another issue. When running your page through the Facebook URL Debug Tool, it's saying that a 502 error is returned. You may need to check with your hosting company to determine why that response is being returned:
developers.facebook.com/tools/debug/og/o...ala-kanker-otak.html

But, in my website page, the old comment from the old domain (www.deherba.com) is gone and show this error message:

Please note that Facebook comments are attached to a specific URL. When you change your domain name, the comments that were associated with the 'old' URL will not work on the 'new' site. There is no way to transfer comments from one URL (or domain) to another.

1. How to rename deherba.com page to deherba.co.id in facebook?

If you run the JFBConnect -> Autotune -> Facebook App tool, it should check and update your Facebook settings properly for the new domain.

2. Why if I click link In the left menu > developer > www.deherba.co.id, it's only show the page with message: This Connection is Untrusted...?

Can you explain this error a little more? I'm not sure what you mean.

I hope that helps explain. If you need anything else, just let me know.

Thanks,
Alex

I'm still seeing the 502 error, as shown in the picture below:

However, on your home page, I'm no longer seeing the "unreachable" error. If you are, let me know. If you did get a 200 code from the Debugger tool, that would have been enough for Facebook to 'reach' that page and see it's contents, which is all that would have been necessary. Other pages may still have issues until Facebook is able to automatically scan them, or you are able to use the Debugger on them.

Finally, unrelated to the above, you look to have sh404SEF installed with the Social Buttons plugin enabled (in the sh404sefcore plugin group). That plugin will re-add the Facebook Javascript library and may cause you other issues with other features.

I hope that helps, but if you run into anything else, just let me know.

Thanks,
Alex

The warning will appear on pages until one of the following has happened:
1) Facebook is able to successfully crawl the page. That can be when the automatically do so every few days or by running it through their Debug tool. If you're getting a 502 error in the debugger, it likely means their automated crawler is getting that error too. Again, you should be able to contact your host to determine why 502 errors are being reported, or at least get some more details on when/why it's happening.
** To note though, the 2nd page you mentioned is *not* showing the warning for me. So, it likely was scanned with a 200 code at some point, which is a good thing.
2) For Twitter, can you explain more? Is there any specific page where it always doesn't show, or does it sometimes show and sometimes not? Can you test in multiple browsers and see if the problem happens there as well?

Thanks,
Alex

Besides, twitter button's problem... Why each time I visit apps.facebook.com/deherba/ show untrusted page, how to solve this. Thank you!

You don't have a valid SSL certificate installed on your website. To use your site within Facebook, you must have a valid SSL certificate or you will get that error.

Regarding Twitter, I see the Twitter, G+1, Pinterest and FB Like button on the page you linked to above. Do you never see it on that page? I'm testing with Chrome on a Mac.

Please let me know how you're testing.

Thanks,
Alex