Handling errors when entering registration key
When you purchase a Guardian license, you will be sent a registration key within a few days. The email will tell you to go to "Admin Page" => "Update License" and to paste the key in.
When you do that, one of two things will happen:
It will say "success: saved settings" and the License Mode will be updated to "Registered Shareware". This is what is supposed to happen.
Or, it will return "error: the registration code you entered is not valid". This usually happens for one of the following reasons:
Make sure you're pasting in the entire block of text, starting with and including "BEGIN LICENSE", and ending with and including "END LICENSE". If you only paste the alpha-numeric data after the hyphen, then you will receive this error.
Or, double-check that the license text does not have trailing blank spaces after each line of text. Some HTML-formatted email programs will add a trailing space to each line of text. License keys copied from these email programs may pick up this extra space. If this happens, you should manually delete each trailing space before submitting the registration key.
In case of problems
If you have any other problems, please contact Fluid Dynamics.
The validation of registration keys is a simple mathematical process. No network activity needs to occur between your script and our systems. Registration keys should work normally on isolated systems.
Update 2015-10-22: a free key is now available for public use.
"Handling errors when entering registration key" https://www.xav.com/scripts/guardian/help/1088.html