Based on my experience the reason for this error is accelerate python library not installed relevant python environment. This way help me to resolved the issue.

(1) First I run this command in my JupyterLab Desktop notebook cell.

import sys

print(sys.executable)

(2) Then this command gives you to path of relevant environment. Now you can installing accelerate directly into the JupyterLab Desktop environment using the following command. You should enter your path instead of below command your path word.

!your path -m pip install "accelerate>=0.26.0"

After that restart your JupyterLab Desktop and check.