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When clicking on listing links from an email sent via Constant Contact, which masks the links with a tracking code that redirects to the given link, the accessed pages produce a server error 500. Most of the page loads, except for the dynamic listing content which the page is meant to display. I've encountered this error NOT from Constant Contact links before, just browsing the site, but our IT guy says "the initial URL is the tracking URL with some java script in it"... then goes on to say that it has to do with java not being updated on our computers, and nothing to do with the server. I think it's just that the server times out before the redirect goes through. Or either way, there's no "javascript in the URL", and javascript and java aren't at all the same thing.

I'd greatly appreciate if someone could help shed some light on what is actually going on here.

See, the initial Constant Contact links look like this:
http://r20.rs6.net/tn.jsp?f=001z7k8t_ktkq_Kgjb6oUCGE25-wLbQOTyP2qtFdWeHpksY8M6c8a3YBKqSSksqdrSR6r5v6g8SPvZg6Y_rsioK4L_ImzStwhewgDhxSBkXR-pgGBX4UxffL52aUybWq7DWOQqts7A14XyLibj3uxR16I2Ja1rXOK1qGbGMBVR_bdQR5IBRTlrB4-bzlizcEW-0bxD3YxZw9gEQ2CORxadlVbQAb5dkqgNFqOu0cPh0NGiQ6n20LPqNWcdSH4_k-VFEv-VkpLHqAoY=&c=1o0_rd9BgTaTWgFZEMcOmhhRsV_4ba_BFc37-icyjV03EV9IE8cUVw==&ch=8T0E5b0urUObuyz3eLOpmV4Qc4QacWH-uslCofeuylK43nqqx4mlMA==

Anyone see any javascript in that URL? I don't. Just a long tracking code, URL QUERIES (i.e., ?f=...&c=...), which are not JS. Sure it's being processed by a Java Server Page, but once it redirects that shouldn't have anything to do with it anymore, should it?

If that redirects to a page that produces a SERVER ERROR, is the responsibility not on the website's part to handle the request? The links are correct. If the listing doesn't show up and it says server error, it does when you refresh. Plus I've seen the same error just when browsing the site, which disappears upon refresh. So... can anyone explain this actually for me please?

Thanks...

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Dani AI

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Short expert summary and practical checklist.

is right: the long tracking URL from your email is just a redirect token used by the mailing service; that by itself does not run Java on the client. A 500 response is an internal server error — i.e., something on the site that receives the final (post-redirect) request failed. See the HTTP spec/MDN for the 500 meaning. (Also: Java and JavaScript are different technologies and fixing one will not fix the other.) MDN: 500 Internal Server Error • MDN: JavaScript intro

How the redirect chain matters: the tracking link issues a redirect (302/3xx) to the final page; the final server then processes that request and can return 500 for many reasons (unhandled exception, DB timeout, input-parsing failure, WAF/mod_security rule firing, resource exhaustion). Tracking links commonly add opaque tokens/parameters that can change the request the server receives, so reproduction and logs are needed. MDN: 302 Found (redirects) • Constant Contact documents that click-tracking uses redirect links. Constant Contact: email click tracking

Concrete, low-effort steps to isolate the fault (can be done by the dev/hosting team):

  1. Reproduce the redirect chain from a shell or browser devtools. Example:

    curl -v -L 'PASTE_TRACKING_URL_HERE' -o /dev/null -w '%{http_code} %{url_effective}\n'

    This shows each response and the final URL.

  2. At the server: search the error log for the request timestamp, full query string and any stack trace. That log is decisive — 500s almost always have a server-side stack or mod log entry.

  3. Check WAF/mod_security and proxy logs; ModSecurity can return 500 if response/request buffering limits or rules are triggered. ModSecurity reference manual (SecResponseBodyLimit)

  4. Quick test: send an email with the un-tracked (direct) URL to see if the issue reproduces without the tracker. If it does not, capture and compare the exact query string and headers between tracked vs direct hits.

If the site owner/host will share the error-log excerpt and the exact redirect URL (or let a developer run the curl test), the root cause can be identified quickly.

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Member Avatar for cereal

Regarding the 500 error, check the error log of your server, an external redirect cannot generate an error like that, unless your server config is accepting some headers set from remote.

A part that, if you look at f, c and ch values, these are base64 strings, concatenated by - characters, by splitting them and decoding you can get some random characters, probably due to a particular character encoding... These kind of string can be used to bundle code or images into source codes, but in your case, this is not the reason of the error: it could if the code was appended to the final link, i.e.:

So, I would check the logs of the server, of the database and the source code that generates the dynamic listing. Bye!

Member Avatar for cilla

Yeah, unfortunately I don't have access to the source code, and nobody else cares to find out or have our programmer look into it, they'd rather just blame it on Constant Contact. I figured to find out the actual source of the problem the code needs to be debugged, logs checked... that sort of thing... on our server's side, I just wanted to clarify that it has nothing to do with the redirect links, which it obviously doesn't. Thanks. That's all I have the power to do. Still no one cares. You have no idea how many errors and bugs there are throughout our site all the time. It's straight ridiculous.

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