Author Topic: avast for mac web protection module stops ical calendar subscriptions  (Read 3890 times)

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  • Guest
After upgrading my Macbook from SL 10.6.8 to Lion 10.7.4 and having installed the latest version of Avast for Mac I face the problem below: In iCal 5.0.3 calendar subscriptions from e.g. won't refresh anymore and additionally I am not able to subscribe to other public calendars. Once I interrupt the web protection module in avast then the subscription and refresh is possible again. I haves checked if there is a problem with web and contacted the programmer.
Has anyone else experienced this behavior?


  • Guest
Any messages logged in console?

I posted previously about opscd running rampant, LION CRL + Avast had issues.


  • Guest
I am the administrator of the mentioned calendar service. I have recieved four reports on users not being able to subscribe to calendars. In all cases the problem has been avast Web protection module. When disabled, everything has worked fine.

I had to add a question to the FAQ about this problem.

I hope this problem gets fixed. Now I have to recommend users not to use avast, or at least disable web protection module.

Offline tumic

  • Avast team
  • Advanced Poster
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The problem is, that your server is sending invalid Content-Length headers. The size send by Your HTTP server is the size of the content even if gzip Content-Encoding is enabled. But in this case, the size given in the Content-Length header has to be the size of the compressed data, not the size of the uncompressed content.

So in other words the problem is in Your HTTP server (I'm pretty sure, this is a known apache bug for some version), not in the avast! webshield. The shield is just doing what it was designed to do - it is blocking broken/malicious pages. And IS currently broken.


  • Guest

Thank you for your reply. The problem is (was) that none of the tested calendar apps accept gzipped data. I still enabled it to make downloads via browser faster. It was actually quite difficult to get the content-length correct (tried multiple different approaches). In the end, I just removed it. Now everything works with or without avast.

No browser and no calendar app had indicated any problems because of this, which is why I wasn't avare of any problems with content-length.

But as I said, now everything works.