my udf:

If you want use this forum it can help you. Good luck.

https://www.cfd-online.com/

I'm not familiar with two phase flow, but your UDF looks good and I have compiled and linked without any error, with liquid source at phase1 and vapor source for phase2.

but I get an error message, it is not like yours.

if you have a simple case may be you can send it to me, I think that I had missed some things.

Are you sure that you had compiled correctly?.

if you use udm in your udf, try to define it before compile.

I think there is no need to use udf to model evaporation and condensation instead you can use the evaporation/condensation module in fluent. i have used this udf recently and there is no problem with it.