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WebSharper 4 -- obscure error if WebSharper output is not specified #934

nightroman opened this Issue Mar 30, 2018 · 1 comment


2 participants

nightroman commented Mar 30, 2018

Given WebProjectOutputDir is missing in the project file and outputDir is
missing in wsconfig.json, dotnet build fails with a very obscure error:

FSC : WebSharper error FS9001: Global error 'The option value was
None↔Parameter name: option' at    at
Microsoft.FSharp.Core.OptionModule.GetValue[T](FSharpOption` 1 option)↔   at
WebSharper.Compiler.CommandTools.ExecuteCommands.Unpack(WsConfig settings)↔
at WebSharper.FSharp.Program.Compile$cont@191-2(WsConfig config, Boole an
isBundleOnly, Loader loader, FSharpList`1 refs, Task`1 wsRefsMeta, Compilation
comp, Unit unitVar)↔   at WebSharper.FSharp.Program.Compile$cont@61(WsConfig
confi g, WarnSettings warnSettings, String thisName, Unit unitVar)↔   at
WebSharper.FSharp.Program.compileMain$cont@271(String[] argv, Unit unitVar)↔
at WebSharper.FSha rp.Program.main(String[] argv)

It is a user error indeed that the output is not specified. But it is not impossible.
It happened to me on converting a WebSharper v3 project to v4.
Due to the obscure error, it took a long time to find my mistake.

@nightroman nightroman changed the title from WebSharper 4 -- not useful error if WebSharper output directory is missing to WebSharper 4 -- obscure error if WebSharper output is not specified Mar 30, 2018


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Jand42 commented Apr 3, 2018

Thanks for the report! Error reporting around unpacking will need to be revised and improved for #664 anyways, so this will definitely will be improved in version 4.3. In the meantime, a descriptive error will be given in the next bugfix release.

@Jand42 Jand42 added this to 4.2.VNext in Releases Apr 17, 2018

@Jand42 Jand42 closed this in 4891566 Apr 17, 2018

@Jand42 Jand42 added the label Apr 17, 2018

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