Deserialization works in program but fails in interactive

I’ve found a strange issue where deserialization of a type works fine in my program, but fails when I run the same serialization in interactive. In interactive I get the following exception:

Couldn't parse config, error=JSON Path: . Failed to serialize, must be one of following types: record, map, array, list, tuple, union. Type is: Configuration.

I haven’t been able to create a minimal example of the issue, but I’ve made a branch on the affected project to demonstrate the issue here.

To see the issue:

1. Place a debug breakpoint here. This is where we try to parse the Configuration type.
2. Run the Lint project test. This will try to lint the provided project, eventually hitting the parseConfig breakpoint above, when it tries to parse the default configuration file. It should succeed.
3. Run the FSharp.Json.Error.fsx file in interactive debug. You should get the exception above, when it tries to parse the same default configuration.

Through this I was able to confirm that the two functions seem to be receiving the same input.

[vincenzoml]

Hi all, I had this issue today, and it was caused by the fact that I had made “private” the type I was trying to parse from json. Removing “private” solved the issue. So maybe the exception is caused by an accessibility problem?

[NicoVIII]

If there is no way (for now?) to fix this issue, I guess a better exception message which points to the real problem would be nice. I was confused, when the thrown exception told me, that my record type is not a record type 😄