Windows 10 and 2012 R2 server. IIS 8.5. php 7.4.14 . xdebug 3.0.2
IDE Net bean 12, or PhPstorm 2020.2

When the web site root is in a network folder share and mapped as UNC path in Internet Information Service , breakpoint are skipped and in xdebug.log are reported as unresolved

for example
[14720] [Step Debug] <- breakpoint_set -i 17 -t line -f file:///share/bla/bla/bla/www/tmp_2.php -n 12
[14720] [Step Debug] -> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/dbgp/xdebug" command="breakpoint_set" transaction_id="17" id="147200003" resolved="unresolved"></response>

But the scrips stop at the first line, and cliccking "Resume Program (F9)" it stops at the xdebug_brak(); line. "Step Over (F8)", "Step Into (F7)",... work .

If the same network project folder is mapped in a local folder using a windows symbolic lync (for example Physical path in iis c:\wwwlocalsite\symboliclinkroot) , xdebug works fine, and stops at every breakpoints.

This problem arises from xdebug 2.8 and above. With php 7.3.20 and xdebug 2.7.2 , using the same php network project folder, and setting the UNC Physical path in IIS, brakpoints are correctly resolved (and hit)