Problems transferring files from iMac to Mac Mini Server due to com.apple.desktopservices

Hello. I have a Mac Mini Server to which all my iMac's connect to via wi-fi and had been transferring files back and forth for 3 years without any problems until a few days ago. Now, I can't transfer files back to the server without having the Finder ask for a password so I can "make changes". There's no problem with taking files from the server to my desktop, but when I try to put them back onto the server the Finder prompts me to type password and it's caused by com.apple.desktopservices. Anyone else have this problem between two Macs? I noticed that people have this issue between a Mac & PC. Thanks in advance.