Failed to external entity “…/htmlhelp.xsl”

I'm building a development version of Wireshark to create dissectors, following the tutorial found in their official documentation

I receive two warnings and four errors. The four errors seems to come from the fact this link cannot be loaded. The errors are:

Build FAILED.
   "C:\Development\wsbuild64\Wireshark.sln" (default target) (1) ->
   "C:\Development\wsbuild64\docbook\developer_guide_chm.vcxproj.metaproj" (default target) (15) ->
   "C:\Development\wsbuild64\docbook\developer_guide_chm.vcxproj" (default target) (118) ->
   (CustomBuild target) -> 
     CUSTOMBUILD : warning : failed to load external entity "http://docbook.sourceforge.net/release/xsl/current/htmlhelp/htmlhelp.xsl" [C:\Development\wsbuild64\docbook\developer_guide_chm.vcxproj]


   "C:\Development\wsbuild64\Wireshark.sln" (default target) (1) ->
   "C:\Development\wsbuild64\docbook\user_guide_chm.vcxproj.metaproj" (default target) (65) ->
   "C:\Development\wsbuild64\docbook\user_guide_chm.vcxproj" (default target) (119) ->
     CUSTOMBUILD : warning : failed to load external entity "http://docbook.sourceforge.net/release/xsl/current/htmlhelp/htmlhelp.xsl" [C:\Development\wsbuild64\docbook\user_guide_chm.vcxproj]


   "C:\Development\wsbuild64\Wireshark.sln" (default target) (1) ->
   "C:\Development\wsbuild64\docbook\developer_guide_chm.vcxproj.metaproj" (default target) (15) ->
   "C:\Development\wsbuild64\docbook\developer_guide_chm.vcxproj" (default target) (118) ->
   (CustomBuild target) -> 
     CUSTOMBUILD : I/O error : Attempt to load network entity http://docbook.sourceforge.net/release/xsl/current/htmlhelp/htmlhelp.xsl [C:\Development\wsbuild64\docbook\developer_guide_chm.vcxproj]
     CUSTOMBUILD : compilation error : file /Development/wireshark/docbook/custom_layer_chm.xsl line 8 element import [C:\Development\wsbuild64\docbook\developer_guide_chm.vcxproj]


   "C:\Development\wsbuild64\Wireshark.sln" (default target) (1) ->
   "C:\Development\wsbuild64\docbook\user_guide_chm.vcxproj.metaproj" (default target) (65) ->
   "C:\Development\wsbuild64\docbook\user_guide_chm.vcxproj" (default target) (119) ->
     CUSTOMBUILD : I/O error : Attempt to load network entity http://docbook.sourceforge.net/release/xsl/current/htmlhelp/htmlhelp.xsl [C:\Development\wsbuild64\docbook\user_guide_chm.vcxproj]
     CUSTOMBUILD : compilation error : file /Development/wireshark/docbook/custom_layer_chm.xsl line 8 element import [C:\Development\wsbuild64\docbook\user_guide_chm.vcxproj]

2 Warning(s)
4 Error(s)
Time Elapsed 00:00:07.72

When I go to the URL directly, I am taken to a blank page. Going through the directory online I can go up to here, but clicking on "htmlhelp.xsl" brings me back to the blank page.

However, although the VS 2015 CMD says the build failed, an executable version Wireshark is built and I can use it with more or less full functionality.

My main issue is I kept on having errors building a C++ dissector (Lua dissectors work just fine) due to LNK errors. I was thinking, because the build is "incomplete", the issues could be arising from a missing file or such.

Hopefully this will help someone with similar issues.

It turns out the file could not be reached because of the company's proxy settings. I have been using IE and the file would not load.

However, when I used Mozilla Firefox, I was able to download the file. I changed the XSL import address to a local directory containing the downloaded file and the import errors were fixed.