Watson and Crick proposed that the two strands of the double helix are held together by hydrogen bonds between complementary base pairs. However, they incorrectly suggested that adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C).

This error was soon corrected, as experimental evidence showed that A actually pairs with T and G pairs with C. This pairing is known as complementary base pairing and is essential for maintaining the structural stability of DNA.

In summary, the error in the Watson-Crick DNA model paper was the incorrect pairing of base pairs. While this error was significant, it was quickly corrected and did not diminish the importance of the paper's overall contribution to our understanding of DNA structure.