Copy GDB failing in Web Tool

[MOlesberg]

I made a script for my organization which copies entire GDB files to new locations using UNC paths. The script functions successfully in ArcGIS Pro in the desktop toolbox. I shared the script as a web tool, and the copy function now receive the "Error 000260: Failed to copy" and "Error 999999: Something unexpected caused the tool to fail" with the same parameters. 

The line which fails is arcpy.management.Copy(GDB, newGDBpath).

[TonyContreras_Frisco_TX]

Does the account that was set up as the ArcGIS Server service account have write access to the UNC location? How large are these FIle GDBs?

[MOlesberg]

The ArcGIS Server service account does have write access to the UNC location? The GDBs are large: 5-15 gigs depending on the mix of rasters, vector data, and attachments.