The phrase 'series of obstacles' is correct and usable in written English. You can use it when referring to an accumulation of hardships or difficulties that must be overcome in order to achieve a goal. For example: "The team had to deal with a series of obstacles in order to reach the summit of the mountain.".
I was forced to use a wheelchair and found a whole series of obstacles.
But any deal would have to overcome a series of obstacles first.
Even in boom times arts management is about surmounting an inexorable series of obstacles.
"Running your own business is a series of obstacles that you turn into opportunities.
The hurdling events combine sprinting with negotiating a series of obstacles called hurdles.
But, he said, he sees "a series of obstacles and a lack of determination" on both sides.
You've got to get him from the start line to the finish by negotiating a series of obstacles and jumps.
Ludwig does not simply clarify my doubts with English writing, it enlightens my writing with new possibilities
Simone Ivan Conte
Software Engineer at Adobe, UK