Compatibility with code written in version 9

@Carmem_BR 

To add to Charlie's post, I shall say a bit more on code compatibility.

> Can I migrate version 9 to version 2021?

Yes, you can.

> Is there a lot of incompatibility?

No, not a lot. The ColdFusion Team strives to maintain as much backward-compatibility as possible. 

You could already check the compatibility of your ColdFusion 9 code as follows:

• Download and install the Developer Edition or Trial Edition of ColdFusion 2021; if you install on the same server, use for ColdFusion 2021 a port number different from the one you use for ColdFusion 9;
• Open the  ColdFusion Administrator of the newly installed ColdFusion 2021. Go to the page Debugging & Logging, and click on the tab Code Analyzer. This is a tool for checking compatibility of your code with ColdFusion 2021.
• Use the following settings:

          Analyze subdirectories (checked checkbox)
          Analyze file types: CFM, CFC
          Validate CFML (checked checkbox)
          Version of code to test: CF11

• Click on Browse Server and select the directory containing your ColdFusion 9 code;
• Click on Run Analyzer.

You can install a new cf version alongside another. There is no provision to upgrade a cf version. At first launch of the cf admin, it would try to identify and offer to import the admin settings of a previous version...but it won't offer that for such a large jump as 9 to 2021. 

As for what to expect compatibility-wise, it will vary. Some find the move trivial, some atrocious. No single document or tool exists that will help assess that move. There's a deprecated features page in the cf docs  but that covers only a subset of possible compact errors. There's nothing to do but try it.  (And while of course you can seek help in the community for issues you may hit, it can be helpful to have the guidance of someone experienced in solving such migrations. I can offer that on a consulting basis, as can others.) 

Finally, as for cores, cf imposes no limit on how many it can use. But as for licensing, cf Standard is priced per 2 cores while cf Enterprise is priced per 8 cores.