Failed to delete some children. This might happen because a process has files open or has its working directory set in the target directory

Error:

Unable to delete directory 'C:\_d\mycompany\WSs\demo\build'
  Failed to delete some children. This might happen because a process has files open or has its working directory set in the target directory.
  - C:\_d\mycompany\WSs\demo\build\classes\kotlin\main\com\mybank
  - C:\_d\mycompany\WSs\demo\build\classes\kotlin\main\com
  - C:\_d\mycompany\WSs\demo\build\classes\kotlin\main
  - C:\_d\mycompany\WSs\demo\build\classes\kotlin\test\com
  - C:\_d\mycompany\WSs\demo\build\classes\kotlin\test
  - C:\_d\mycompany\WSs\demo\build\classes\kotlin
  - C:\_d\mycompany\WSs\demo\build\classes
  - C:\_d\mycompany\WSs\demo\build\generated\source\kapt
  - C:\_d\mycompany\WSs\demo\build\generated\source\kaptKotlin\main
  - C:\_d\mycompany\WSs\demo\build\generated\source\kaptKotlin\test
  - C:\_d\mycompany\WSs\demo\build\generated\source\kaptKotlin
  - C:\_d\mycompany\WSs\demo\build\generated\source
  - C:\_d\mycompany\WSs\demo\build\generated
  - C:\_d\mycompany\WSs\demo\build\kotlin\compileKotlin\caches-jvm\inputs
  - C:\_d\mycompany\WSs\demo\build\kotlin\compileKotlin\caches-jvm\jvm\kotlin
  - C:\_d\mycompany\WSs\demo\build\kotlin\compileKotlin\caches-jvm\jvm
  - and more ...
  New files were found. This might happen because a process is still writing to the target directory.
  - C:\_d\mycompany\WSs\demo\build\kotlin\compileKotlin

Solution:

The problem is that you have multiple Gradle processes that are still holding locks to your files.

You can try running gradle –stop when this happens to stop any daemons that are running in the background (this usually helps).

You can also check the state of your daemons by running gradle –status. For me this outputs:

The problem is that you have multiple Gradle processes that are still holding locks to your files.

You can try running gradle --stop when this happens to stop any daemons that are running in the backgorund (this usually helps).

You can also check the state of your daemons by running gradle --status. For me this outputs:

If you notice anything there, there may be an issue.

Although –no-daemon and –no-parallel may be helpful, they will only serve to mask the true issue.

When this occurred in my situation, I discovered that processes were running in the background as a result of tests that never ended. Check for open or unfinished processes across all of your threading and/or coroutine usage.

I also experienced this when I used ProcessBuilder to launch another Java process, however, it failed to terminate.