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Migrate Classic ASP and Visual Basic application into .NET 4.8/ .NET Core/.NET 5.0

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We have a few legacy applications developed using Classic ASP and Visual Basic. Now we are thinking to migrate these applications into .NET(4.8/.NET Core/.NET 5.0/.NET 6.0).  We are looking for some information regarding the Licensing part. I have seen that if we have MSDC subscription, free license will be provided for converting upto 10000 lines of code. Questions are below

1. What are the recommendations in terms of choosing .NET version for migrations.

2. Would that be possible to use the same free license for multiple applications with lines of code less than or equal to 10k?

3. We have many application with more than 10K lines of code.? what kind of additional license needs to be purchased?

4. Are you forecasting any challenges while using this VBUC for migrations?

5. How much amount of manual effort requires for the issues encountering during the upgrade?

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  • Mobilize.Net Staff

Hello, thanks for your interest in our tools. Let me try to address your questions:

MSDN: The license will let you migrate one application of up to 10,000 lines of code and put it into production.

1. The recommendation is to go with the latest version of the Framework, however it is important to note that .NET Core / .NET 5 don't have support for all the libraries and you might need some additional manual work. Things such as remoting (when converting COM+ objects) or the VB compatibility libraries will not work there.

Also, some third party libraries might not have .NET Core support. This will depend on the things you use on your application.

2. No, the VBUC is licensed per-application. The license file itself will be tied to a particular application or set of applications.

3. Please send an email to [email protected] to get specific pricing for your particular application. The pricing will be based on the size of the application. We can also offer some help with the remaining manual work if you need.

4. There will always be some manual work required to stabilize a migrated application. This might be because of unsupported components or changes between the platform. This will depend on your application and how it is written. Our docs have some information of common issues and how to address them: https://docs.mobilize.net/vbuc/issues-troubleshooting

5. Same answer as above. The manual effort will depend on the type of components used in the application. Normally you will require between 1/5 and 1/10th of the time it would require to do a manual rewrite.

Typical VB6 applications will have around 95-98% of automation. Meaning 2%-5% of the lines will require some kind of manual change.

You also need to take into account testing. Even if you got 100% automation you still need to test the entire application because all the code is re-generated.


Please let us know if you have any additional questions and please send an email to [email protected] to get the pricing information.


- Will

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  • Mobilize.Net Staff

You're welcome.

The current version of the VBUC doesn't have 4.8 as an option, but selecting 4.7.2 will not prevent you from using it. It will be updated once you open it in Visual Studio.


- Will

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  • Mobilize.Net Staff


It looks like your application is ready to be opened.

- PreProcessInfo contains info compiled by the VBUC regarding the source application.
- Upgraded. Folder with the C# converted code
- UpgradedSupport. Folder with herlper classes required by the converted code.

You can now go to Upgraded folder and open the VS.Net solution contained there and check the C# code.







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  • Mobilize.Net Staff

Hello Prasad, 

Please reach out to us at [email protected] where we can assign you an account manager and a solutions architect that will help you with a license you can use in production and a support package that can help you complete the modernization successfully.

- Will

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