Hi,
I try to make all post-processes using Blender because of GPU compositing support. Now it is so fast!
I want to keep my old workflow, so I saving render with all needed passes into EXR multilayer image (including cryptomatte).
Next I’m creating new blender file (as I used Photoshop in the past) for compositing (file attached). Then I’m doing all stuff and create cryptomatte nodes with image option. All works fine when Blender read external image, but wehn I pack EXR image into Blender, then cryptomattes don’t work any more. Please tell me why?
cryptomatte_v01_fixb_01.zip (3.6 MB)
And why when I connected cryptomatte passes from EXR file to cryptomatte node nothing happened? Why I always have to open the same image into cryptomatte node?
Please help me 
Use Add > Input > Image to import your image, don’t drag and drop. Make sure your cryptomatte EXR is Float Full (32-bit). Them use cryptomatte legacy node.
In this scene I have color passes in 16-bit and data passes in 32-bit to reduce file size:
Big thank you for answer. This cryptomatte (legacy) node will be soon remove from blender. I’m very interest how should look like setup with current cryptomatte node and packed EXR 32 bit file with all data. Can someone share with me correct setup of my simple scene?
How did you save the EXR? I think some compression settings can f#ck up the passes.
EDIT: I just tried the file you shared and it does seem to be a problem with Blender not being able to read the cryptomatte passes when the image is packed. I unpacked it and saved it to a local folder and then everything works as expected, I’d say this is worth a bug report
!!YES!! I thought that too, so I’ll report this probably bug. Thank you for your reaction