Change RDS reserved instance because is not available when creating database

If you really want to use DB.m4, enable the Include previous generation classes toggle button, you'd see db.m4.

However db.m4 is previous generation class and if you want to utilize db.m5(Here is the comparison) then I'd suggest you to open a billing support case and specify the AWS region, RI type and RI ID and mention why you don't want to to use this RI. How to log billing case.

Once your RI gets canceled, then you can purchase db.m5 and provision your database.

Don't provision the database until you get this sorted if you really want to utilize the RI's benefit with db.m5 otherwise, just use the first line suggestion, you are good.

Hey, I have the same issue, not able to see db.m4 instances We already purchased one RI db.m4.4xlarge and not able to use it as its not coming in drop down when trying to modify the existinng db instance.