The latest set includes 421 districts. "Almost unnoticed,the country’s Central Statistics Office (CSO) and the Independent Directorate of Local Governance (IDLG) have come up with a joint, consolidated list of how many districts Afghanistan has. It has handed this list over to the Independent Election Commission (IEC) that has used it in preparing the elections. The number is: 387. [Or 387 "districts" and 34 "provincial center districts" for 421 districts in total]. Here is an external link to a spreadsheet of some of the more recent generations of district sets.
The list below includes districts with links to other Wikipedia pages. It doesn't correspond with any particular district set. It lacks a number of districts currently recognized by the Afghan government, and lacks some others that are popularly but not officially recognized.