Edit: I think I understood the problem. This is the directory location for temporary files. With the update of the FME version, the path to my directory has to be changed (a "UNC" has been added at the beginning). I changed the location of this directory in FME 2020 (to point it to a server with more disk space) ... But now (on the 2021 version) I can't change this... Do you know where can I do this manipulation?

@theodrogo​ This article describes the various places FME can use for temp space. For performance reasons, it is best to have the temp space on the local machine, preferably on an SSD drive.

Edit # 2: Sorry for answering myself lol. I solved the problem, and if it can help someone, here's what I did:

- I went to check the location of my temporary variables (in windows: Control Panel | System and Security | System | Advanced system settings | Environment Variables)

- I modify the path of FME_TEMP. Instead of using \\\\ myserver \\ etc., I used a shortened path. To do this, I mapped a new network drive (example: Z: \\ FME_TEMP), and I used this path to specify the location of FME_TEMP in the windows variable environment.

- I restarted FME Desktop 2021, and everything works.

- I also checked that the temporary files were placed in the correct FME_TEMP folder. And now, feature caching is back to work!

Ciao!

@Mark Stoakes​ 

I just saw your answer right after posting my edit # 2. I actually used this article to correct a part of the problem. Thank you so much ! :)

@Mark Stoakes​ 

And for the question of performance, I would like to use an SSD locally, but I use a VM and it is impossible for me to add a disk to it ... So I compromise to lose a little performance by storing them on my server .. Hope I can change that someday!