Solutions often fail on edge cases because of incorrect assumptions about the input. For instance, if the input array is assumed to be non-empty, your solution may fail when given an empty array. To handle edge cases, carefully analyze the problem’s constraints and think about extreme inputs, such as minimum or maximum values, empty arrays, or repeated elements. Testing with corner cases like single elements, all elements being the same, or very large inputs is essential. Also, consider any special cases that arise from the problem's constraints and handle them explicitly in your code. Thorough testing and considering all edge cases ensures that your solution is robust and comprehensive.