The most common and most likely answer to this crossword clue is the 9 plus 2 plus 4 letter word MULTITUDE OF SINS
I've seen this crossword clue in The Guardian
M
U
L
T
I
T
U
D
E
O
F
S
I
N
S
Buddy explains!
The straight part
We know that "many errors" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case many errors = multitude of sins.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.