PowerShell was written for Windows, which assumes an underlying filesystem where case does not matter. When you enter a PowerShell command, the program reads whatever you type, and then matches it against its idea of what the case ought to be and redisplays that.

The help-message for PowerShell shows the option as -Version:

-Version
    Starts the specified version of Windows PowerShell. 
    Enter a version number with the parameter, such as "-version 2.0".

The error message is saying that it expected to find a match using the filesystem's notion of the fully-spelled name. You will probably have better success if you use the mixed-case names as indicated in the help-message.

PowerShell was written for Windows, which assumes an underlying filesystem where case does not matter. When you enter a PowerShell command, the program reads whatever you type, and then matches it against its idea of what the case ought to be and redisplays that.

When this question was asked in August 2016, the help-message for PowerShell showed the option as -Version:

-Version
    Starts the specified version of Windows PowerShell. 
    Enter a version number with the parameter, such as "-version 2.0".

The error message is saying that it expected to find a match using the filesystem's notion of the fully-spelled name. You will probably have better success if you use the mixed-case names as indicated in the help-message.

That message was changed about a year later, in issue #4958 which stated in effect that the feature did not actually work. OP's question dealt with asking the reason for the error message, which is explained by the message-file (a partly-implemented feature, which has since been removed).