The serial key is not valid

We are trying to use a license that was purcahsed 4 years ago on a new application, (it is working on existing application developed) but when we run the application we get this error:
“The serial key “” is not valid. You are probably using serial key for an older version of the product. Please purchase an updated license to use this product.”
We have the licences for 2.7, using these version of the nuget package: 27.3.30.1253

Can you explain why we are getting this error?

It seems like you’re not getting the right version, the expected version 27.3.30.1253, in runtime.

Please check this:

string version = ComponentInfo.FullVersion;

What value do you get?

I think this is becase we are trying to build this in a .Net Core function app (.Net Core 3.1). The older app that we had this working on was a .NET 4.6.8, which works

It appears that this licence does not allow us to use this version of the framework with a DotNet Core app, using the latest version of GemBox.Document (33.0.310.1483) we get the error described above:
“The serial key “” is not valid. You are probably using serial key for an older version of the product. Please purchase an updated license to use this product.”

Can you advise if this is correct and what I can do to fix this?

Yes, you are using the latest version of GemBox.Document, but you have a license for an older version.

Note, GemBox.Document 2.7 doesn’t have support for .NET Core, see the Version History page.

To use the latest version you’ll need to purchase an upgrade license.
I hope this helps, let me know if you need anything else.

Thanks Mario, how much would it cost to upgrade, my company purcahsed the GemBox.Bundle 1 Developer Licence (ESD)

If you have GemBox.Bundle, then you have a serial key for a newer version of GemBox.Document.

Can you please send us your order’s ID, or email address with which the order was purchased, or any serial key from your GemBox.Bundle license?
You can send it via email or submit a support ticket, see the Contact page.

Anyway, the price of GemBox.Bundle - Upgrade for 1 Developer License is $1080, see the price list page.