It depends on what you call an error, please be more specific and post new question.
The value depends on the type and severity of the the error. If nothing else, it contains two cents' worth of copper.
what is the value of 1945d penny
The rarest and most valuable Lincoln cent that isn't an error is the 1909-S with VDB on it. The rarest and most valuable error Lincoln cent is the 1943 copper penny.
what is the value of a 1912 lincoln wheat penny
Face value
This type of error of misstruck coins is called 'Brockage'. A Lincoln penny with this error is valued at $35.00
The value depends on the type and severity of the the error. If nothing else, it contains two cents' worth of copper.
It's still only one cent. This is NOT a mint error.
A 1999 penny with an 'off-center' error is worth $3.50.
what is the value of 1945d penny
The rarest and most valuable Lincoln cent that isn't an error is the 1909-S with VDB on it. The rarest and most valuable error Lincoln cent is the 1943 copper penny.
what is the value of a 1912 lincoln wheat penny
Lincoln head 1927 D penny
Ask another question and include the date and type of error on the penny.
You will have to take it to someone to be seen. Value if any, depends on the cause of this error. It may be a "Striking" error or a altered coin.
Face value
Missing letters and numbers is a very common error caused by filled or worn dies and adds nothing to the value of the coin.