<name> is not a valid solution name.
This error generally occurs when the command File.NewProject has been entered in the Command window or Find/Command box with an incorrectly formatted value for the argument /sln:solutionname.
To correct this error
Re-type the command syntax and omit the optional argument /sln:solutionname. A unique solution name will automatically be generated.
—or—
Check that the solution name does not contain leading or trailing spaces and is not a reserved word. Reserved words include NUL, CON, AUX, COMx, or LPTx, where x is a digit 1-9.