<Error message>
Error: Exploration Point dse1_utmc_tomcont_top_1 reported: Verilog HDL File I/O error at xxx.v(1): can't open Verilog Design File "<file path>/xxx.v"

Category: Quartus® Prime
Tools: Quartus® Prime
device:-


If the path of the include file is specified as a relative path, it will be a newly generated QPF file (project folder in dse), so the v file cannot be specified and an error has occurred.

In Exploration > Design File Setup in DSE II, select Create design archive from Quartus project and check Discover and include source files missing from project settings
If you're running in a script file (.sh), add --auto-discover-files-on to your command.