Unable to upgrade from v.12 to v.13

[pmcco1214 0]

I bought a license to upgrade Nitro Pro to Nitro Productivity Suite v.12 on Nov. 19, 2018. I was able to activate the license and have been using Nitro Pro with no problems since then. Today I saw that there is a v.13 so I downloaded and installed it. I was asked to activate it but when I tried to activate the license I received in Nov 2018, I received an error message saying "The serial number does not exist". I went through the maze of searching for the license number and generating a new certificate, uninstalling Nitro Pro, deleting all Nitro Pro installers from the downloads directory, downloading the installer for v.12, and was able to install it. The license number was already activated. I then downloaded and ran the v.13 installer again and got the error message saying the serial number does not exist again. What do I need to do?

[AllainU 0]

Hello @pmcco1214,

Thank you for reaching out to us through our Community Forums!

Please be informed that 'The serial number entered does not exist' means the serial number you are trying to activate is for a different version of Nitro Pro. Looks like we need to uninstall the current version of Nitro Pro on your computer and install Nitro Pro 12. We then activate it using your serial number. Kindly follow these steps:
 
1. Uninstall Nitro Pro from your computer by going to Control Panel > Programs > Programs and Features then reboot the machine.

2. Please clear all your downloads folder or delete all downloaded Nitro installers. This step is important because we noticed that if you are saving all the installers and you download them in the same folder (like the downloads folder), the EXE can pick up any MSI installer in that folder and you may pick-up one of the older builds instead of the newly downloaded package.

3. Download your Nitro Pro 12 using these offline link/s:

x32 http://install.nitropdf.com/professional_12163574/en/retail/nitro_pro12_ba_x86.msi
x64 http://install.nitropdf.com/professional_12163574/en/retail/nitro_pro12_ba_x64.msi 

If you are unsure if your machine is using 32 or 64-bit, please refer to this link: https://kb.gonitro.com/knowledgebase/#/search/64/000003790 

4. After installation, you can activate by opening Nitro Pro, clicking on the Help tab > About Nitro Pro > Activation and entering your serial number.

Thank you for choosing Nitro and I hope this helps!