pfsense cannot define table Cannot allocate memory or DHCP fail

It happened to me at the end of April and at the beginning of May in different pfsense boxes, and it took me by surprise that it was a common error during those weeks.

Pfsense??? How??? I never had problems with it!!!!

Let me tell you about the errors I saw on my boxes:
A. Users reported that "they were not able to surf the web", so by checking those workstations I noticed the missed their IP address. Normally they get 192.168.1.x, but all they got 169.254.x.x... and it was not for a damaged cable or port, nor a damaged switch as I was guessing, it was the DHCP service having problems.

B. Then, in the upper right corner on pfsense admin console I saw something like this
There were error(s) loading the rules: /tmp/rules.debug:19: cannot define table bogonsv6: Cannot allocate memory - The line in question reads [19]: table persist file /etc/bogonsv6]

In my case I got a 26 (among others) instead of 19, but the error was the same.

So I found the problem and the 2 steps solution:
There's something called Firewall Maximum Table Entries that after some time gets lack of space (by default size is 1,000,000), and cause the symptoms.

Yes, reboot your pfsense can help, but it won't solve the problem, it will be just temporally.... so do the following:

1. If you have an old pfsense version (2.3 or older).... in other words something that looks like this






There's a bug, so you need to upgrade to pfsense version 2.4.x of something that looks like this







2. Once the update is done go to System-> Advanced-> Firewall / NAT and modify the Firewall Maximum Table Entries to more than 1,000,000 also modify Bogon networks Update Frequency both according to your box capabilities.

3. Reboot pfsense.