Breakdown of Das kleine Missgeschick ist kein Problem.
sein
to be
klein
small
kein
no, not any
das Problem
the problem
Questions & Answers about Das kleine Missgeschick ist kein Problem.
What determines the gender of Missgeschick?
The gender of a noun with a prefix is determined by its base word. The base word here is das Geschick (skill, fate, or destiny), so das Missgeschick is also neuter. The prefix miss- (meaning bad or wrong, similar to the English mis-) never changes the gender.
Why does the adjective kleine end in -e instead of -es to match the neuter noun?
Because the definite article das already clearly shows that the noun is neuter and in the nominative case. When the article does this heavy lifting, the adjective takes the weak ending, which is just -e. If there were no article, it would take the strong ending: kleines Missgeschick.
Could I say ist nicht ein Problem instead of ist kein Problem?
It would be grammatically understandable but sounds very unnatural to a native speaker. In German, when you want to negate a noun that would normally use the indefinite article ein (a/an) or no article at all, you almost always use kein. Think of kein as the standard translation for 'not a'.