New Drobo 5C incompatible with WD 3 TB drives

I am using a disk pack from an older Drobo FS. I reformatted the drives using the Mac Disk Utility and even ran Disk Warrior on them to insure they were okay. I can place each drive in a USB toaster and have complete access to it via USB but when I put it in the 5C, it only says it’s incompatible. I can’t do anything else. How can I use these pre-used drives in the new Drobo?[hr]
Interesting situation. I had one Western Digital red label (NAS) drive 4.0 TB that was being held in reserve for a Drobo Gen 3. I pulled all the 3.0 TB drives and stuck this one 4.0 drive in. It works. I’m thinking the new firmware no longer works with the WD Green drives. That would certainly explain why my Drobo FS stopped working with all 5 drives in it. I put in a ticket with tech support to help with this. The drives that no longer work are the WD30EZRX model. The drive that works is the Western Digital WD40EFRX which also has NASware 2.0 on the label.
Why would one type of drive be suddenly incompatible after working for several years? BTW there is no compatible drive listing on the Drobo web site for the new 5C.

Solved with the help of Tech Support. I had to remove all drives and do a pin reset. Then I inserted 2 drives and through the Drobo Dashboard under Tools, did a reset. After the reset, the drives were able to be formatted. I then inserted the remaining drives one at a time and did a dashboard reset followed by formatting. Tech Support thought that because I formatted the drives first using the Mac disk utility app that caused the problem. I’m finally a happy camper with my new Drobo 5C.

Glad you got it working!