Unpacking in Python:

• Imagine a function that returns multiple results, like a grocery list with several items.
• Unpacking allows you to assign each item on the list to a separate variable in your code.
• It's like taking things out of a bag one by one and putting them in designated spots.

The Error:

• The error pops up when you have more "spots" (variables) than items (returned values) or vice versa.
• If there are fewer variables than returned values, you're missing spots for some items, and Python doesn't know where to put them.
• On the other hand, if there are more variables than returned values, you have extra empty spots and not enough items to fill them all.

ValueError is a standard Exception raised by various methods that perform range-checking of some kind to signal that a value provided to the method fell outside the valid range. Python functions can return multiple variables . These variables can be stored in variables directly. This is a unique property of Python , other programming languages such as C++ or Java do not support this by default. The valueerror: too many values to unpack occurs during a multiple-assignment where you either don't have enough objects to assign to the variables or you have more objects to assign than variables. 

 More info:    http://net-informations.com/python/err/value.htm  

Another case may be regarding looping over dictionary. If one is looping on any dictionary with key and val both without using iteritems(), one will face this error:

a = {'test': 1, 'test 1': 2} 
for k, v in a:
    print k

It will give you that error but instead of one should use it like this:

a = {'test': 1, 'test 1': 2}
for k, v in a.iteritems():
    print k

Still more information can be useful!

Thanks, Priyesh Solanki