Spark File transfer problem between two different

Hi,

I am using Spark and Openfire from Many days/years.

some of my clients are using spark 2.5.8 and some of them are using 2.6.3 (who join recently)

But I am facing problem regarding file transfer between these two clients.

Will you please help me??

While sending file user get message like "due to some error file not transfer" or sometime it won't give any notification to user

Thank you