GET request failed

Why might this error occur?

GET undefined (undefined)

Answer 1, authority 100%

Check here, it might help 🙂

Answer 2, authority 50%

Obviously, some value is substituted into the JS’om request, that’s where undefinedis now the value of some variable, i.e. you need to find which variable is not defined and fix it 🙂
PS: undefined is a JavaScript data type, the word undefined is translated as undefined