Ubuntu – Bash: echo: write error: Invalid argument

You've got it over multi lines, but have the ;.

Your script should look like this:

#! /bin/bash

echo "Start folder create..."
find . -name "*.zip" | while read filename; do

  foldername="${filename%.*}"
  mkdir -p "$foldername"    
  mv "$filename" "$foldername"
  echo "made directory $foldername"
done

The > redirection is done by shell, not by echo. In fact, the shell does the redirection before the command is even started and by default shell will overwrite any file by that name if exists.

You can prevent the overwriting by shell if any file exists by using the noclobber shell option:

set -o noclobber

Example:

$ echo "new text" > existing_file.txt

$ set -o noclobber 

$ echo "another text" > existing_file.txt
bash: existing_file.txt: cannot overwrite existing file

To unset the option:

set +o noclobber

You won't get any option like taking user input to overwrite any existing file, without doing something manual like defining a function and use it every time.