Need Help migrating some old assemblies

Dear Developers,

I need some help migrating some old assemblies to run with the new ensage. For eg. I need to load Showillusions assembly of Mr. Jumpering and while trying to build it, I am receiving the following errors:

CS0103 The name 'ObjectMgr' does not exist in the current context ShowIllusions

CS1579 foreach statement cannot operate on variables of type '?' because '?' does not contain a public definition for 'GetEnumerator'

Please do help me. Thank you in advance