Hi,
Note that the other user on this thread was getting that error when saving the HikaShop configuration and only for that page.
That happens sometimes because of hosting security systems but other pages of the backend still work just fine in that case.
However, if you can't access any page of your website backend, then you don't have that problem. In that case, it's probable that a security system flagged your IP address as potentially harmful and banned it. So whatever you do, you can't access anything in the backend from then on.
In that case, there are several things to do:
- turn off that security system if you know what is causing this.
- try accessing your website backend from another IP address (another internet connection). That should normally allow you to access the backend and if it comes from a security extension, you can disable it temporarily to check with the other connection if it really comes from that or not.
- once you identify which extension of your website / software on your server is doing that, check if they have some kind of whitelist to enter your IP addresses so that you don't get banned in the future.