[Glass] error upgrading stone: become is not allowed

[Johan Brichau via Glass]

Hi,

In the conversion of a Gemstone 2.4.4.1 stone to Gemstone 3.2, I hit an error in the final step when loading our application code:

a ImproperOperation occurred (error 2426), become is not allowed on aNPGsFileWrapper, 'One object is a GsFile or RubySocket while the other is neither'
Error Category: 231169 [GemStone] Number: 2426  Arg Count: 2 Context : 1906733569 exception : 4489410561

We indeed have a subclass of GsFile, called NPGsFileWrapper
Migrating the instances on application load seems to wrong, though both the old and new class are ‘NPGsFileWrapper’ (see stack context of the invocation of become: below)

5 NPGsFileWrapper (Object) >> become:           @4 line 112   [methId 59070977]
    receiver [4489369089 sz:6 cls: 4487621633 NPGsFileWrapper] aNPGsFileWrapper
    anObject [148062465 sz:4 cls: 6802930945 NPGsFileWrapper] aNPGsFileWrapper
    self [4489369089 sz:6 cls: 4487621633 NPGsFileWrapper] aNPGsFileWrapper
    prot [10 sz:0 cls: 74241 SmallInteger] 1 == 0x1

Any way to circumvent this issue in the upgrade?
Or do we need to move away from having instances of classes that are subclasses of GsFile before we attempt to upgrade?

thx
Johan