I am not able to open the exercise --> DIY Exercise 3-1: Create an API specification with RAML. Whe

What browser are you using? Have you tried clearing your cache(s)? If clearing cache(s) and trying different browsers doesn't work, you can access the DIY instructions in the downloadable assets folder (the one with the snippets document, extra JARs, etc.). There should be a PDF called "MUFundamentals3.9_DIYexercises_07mar2018" (date may be different).