Sometimes photos can develop without ever ending. The software seems to continue working for hours. 

Note that it may take longer to develop depending on the amount of photos that have been submitted. 

Here's the guide to simply restart the development of the photos:

1) Make sure that the source photos are imported into your computer: 

For Windows computers, go to: File Explorer / Documents / Exposio / Shooting Date / Sources

For Mac computers, follow the whole process below: How to recover your source photos on Mac

2) Once you have found your source photos, close the Darkroom/Chambre Noire software. 

3) Open Darkroom software again and press ESC key when asked to insert SD card. 

4) Select the third icon from the left of the top menu to import the photos from a folder. 

5) Go to the folder with your source photos. 

For Mac computers, it is important to create a new folder on your desktop. Once this is done, transfer the source photos from the Exposio Alias folder to this new folder. The Exposio Alias folder is not accessible through the software. 

6) Select the first photo in the folder. Normally, all the source photos in the folder will be added correctly in the software. 

7) You can start developing the photos again.