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I can’t open my books, I get an error message

If it happens in school

If the computer or laptop is connected to the school network and the error repeats, it is most likely that the school’s firewall or proxy server are causing the error.
Please copy the URL of this page and send it to the school’s IT Team with the following message:
“Classoos provides eBooks to my department but they are being blocked by the firewall or proxy server. Could you please read the information in the link?”

How to fix the problem in school

  • Add the domains: classoos.com & kalsefer.com to the firewall’s whitelist
  • If Smoothwall is the school’s digital safety provider, please let them know about this via this link: https://kb.smoothwall.com/hc/en-us/requests/new
  • Click here and then on “book preview” (below the cover image) to see if the problem has been fixed. You should be able to scroll through the pages.
  • If the problem persists, check whether this is a proxy issue. Add the domains to an SSL Decryption bypass which will prevent any domain packets from being decrypted and inspected.
  • Still not working? Let us know


If it happens outside school

Reload the page or log in to your account again. If the error repeats, please contact us and we will try to sort it out with you.

Can’t find an answer?

Contact us and we’ll get back to you as soon as we can