Often failed experiments, in their failure, give an indication of an entirely new direction. Many groundbreaking discoveries are made that way.

For example, the discovery of synthetic dyes came about from trying to synthesize quinine.

https://en.wikipedia.org/wiki/William_Henry_Perkin

The discovery of the vacuum tube was an accident resulting from Edison playing round with light bulbs trying to figure out why the filaments were breaking.

https://en.wikipedia.org/wiki/Thermionic_emission