The Kunena team has announce the arrival of Kunena 7.0.3 [K 7.0.3] in stable which is now available for download as a native Joomla extension for J! 5.4.x/6.0.x. This version addresses most of the issues that were discovered in K 6.2 / K 6.3 / K 6.4 and issues discovered during the last development stages of K 7.0
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Solved
SOLVED: Edit existing posting: "You don't have permission to access /forum on this server."
Sorry I am going to go back to a previous topic just because I thought some of the context was confused about what was being said.
Regarding mod_security this is a server thing, has nothing to do with Kunena or Joomla extensions. mod_security is something installed with Apache that basically helps secure actions people take on your website (such as submitting a web form).
Can you please post a link to the topic this issue is occurring (you can use the confidential tags if you like). We really need to determine who is spitting out the error. It might make sense to put your Joomla installation in Debug Mode, and increase the error threshold to Maximum to see if a more specific error is returned.