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As providing quality technical support for our users requires continuous effort on our side, we do expect our users to play fair and are not able to offer any help once the original trial period expires.

Thanks for playing fair. Do do appreciate it as it takes considerable effort on our side to provide a maintained and supported product.

The problem you are experiencing is most likely caused by the Keil trying to compile a C++ file as an assembly file, or vice versa. In order to diagnose it, please follow the steps below:

1. Try narrowing down the problem to a specific source file. Check the build output (View->Output) to see what files are built just before the problem triggers. Then try building that specific file by opening it in Visual Studio and pressing Ctrl-F7 (or right-clicking in Solution Explorer and selecting “build”).
2. Once you can reproduce the problem with a specific file, please check its type and input language via File Properties. If you are not sure, please let us know the file extension, the values of Configuration Properties -> Item Type and Configuration Properties -> C/C++ -> Advanced -> Compile As, and also the exact build output.

We have tried reproducing the issue with VS2019, however could not get the behavior you described. Based on the screenshot, it looks like VisualGDB is trying to save the solution before creating the project and Visual Studio fails to complete the save. Please try updating VS2019 to the latest version and also check if the problem can be reproduced when creating a new GCC-based project from scratch. If not, please try comparing the working and non-working setups to narrow down a specific setting that triggers the issue, so that we could add a workaround on our side.

Thanks for the update. This looks like some of the macros (e.g. portFORCE_INLINE) was not properly expanded. Most likely, this happens because the Keil project overrides some of the advanced settings that were not picked up by the VisualGDB’s project importer.

We have just published a detailed tutorial on extracting comparing the build command lines used by VisualGDB and Keil: https://visualgdb.com/tutorials/arm/import/diagnose/

Please feel free to follow it. As you have already pinpointed a specific source file, you will only need steps 20-25, although we advise reading through the entire tutorial in order to understand the role of the RSP files and various build settings.

If you are not sure, please share the build flags for the problematic file from both Keil and VisualGDB, and also confirm that you can reproduce the problem by building the file manually via command line (per step 22) and we will help you find the root cause.