Contradiction with Job 3:20
While Ecclesiastes 11:7 describes light as sweet and desirable, Job 3:20 questions the purpose of giving light to those who suffer, implying that light (life) is not always sweet.
Job 3:20: Wherefore is light given to him that is in misery, and life unto the bitter [in] soul;
Contradiction with Jeremiah 20:14
Ecclesiastes 11:7 speaks of the enjoyment of light (life), whereas Jeremiah 20:14 curses the day of one's birth, signifying despair rather than enjoyment.
Jeremiah 20:14: Cursed [be] the day wherein I was born: let not the day wherein my mother bare me be blessed.
Contradiction with Ecclesiastes 2:17
Although Ecclesiastes 11:7 reflects on the pleasantness of light, Ecclesiastes 2:17 expresses a hatred towards life, finding it vexatious and not sweet.
Ecclesiastes 2:17: Therefore I hated life; because the work that is wrought under the sun [is] grievous unto me: for all [is] vanity and vexation of spirit.