The wait is finally over. I'm super excited to bring PetFlux to you all -- a P5 -> P4 converter, the product of three years' worth of hard work and self-study into programming and reverse engineering. Simply run your P5 pets through this utility and they'll be compatible with Petz 4. Converted pets will be placed in a subfolder, aptly named "Converted Petz", in whichever directory the pet files are located in.
Note that you can't convert pets who are pregnant/have dependents. External breeds and hexies work just fine. If you encounter errors in PetFlux, please email me the pets you're having problems with (the P5 versions AND the converted versions -- unless the pet didn't convert, then obviously just send me the P5 file, haha).
The bug that caused some pets to trigger the "out of memory" error in Petz 4 has been fixed.
Fixed the "arithmetic operation resulted in an overflow" bug.
Fixed a bug wherein trying to add a file that triggers an exception would result in that file not properly being removed from the list.
Pets using external breeds with hexadecimal IDs ending in 00 will most likely not convert properly, and will trigger the "out of memory" error upon the game loading them.
Known affected breeds: Catahoula Leopard.dog
If you have a pet with this issue that you want converted, please email it to me.