::HtmlHelp function returning NULL which resulted failed to launch .CHM file

Question

We have 32 bit desktop application which we are using ::HtmlHelp API to launch the Html help content. This was working prior and I have observed that some what Windows 2019 edition, We are not able to launch the help content. Which always returning NULL. Find the below code snippet for your reference.

CString chmPath = "C:\Sample.chm";
DWORD data = 1000;
HWND window = ::HtmlHelp(NULL, chmPath, HH_HELP_CONTEXT, data);
Now, Always window returns NULL which resulted failed to launch Html help content.

The below ShellExecute command is working. But, I would like to know. What is the best option to launch the HTML content in MFC and C++ application. Because we are using :::HtmlHelp many years, we did not see any issues.

DWORD data = 1000;
char path[]= "C:\Sample.chm";
sprintf_s(parms, _T("-helpID %d Help content path:%s"), data,path);
HINSTANCE retval = ::ShellExecute(NULL, _T("open"), _T("hh.exe"), parms, NULL, SW_SHOW)

Can you please help meon this.

Answer 1

Hi

Thank you for posting your query.

Kindly follow the steps provided below to resolve your issue which I found in a forum with the same issue you have here is the link for that https://social.msdn.microsoft.com/Forums/en-US/8c0e5c00-57bc-4308-86fc-9cea43f3ce42/failed-to-launch-help?forum=vcmfcatl

To eliminate the 'Failed to launch help' popup, make a MyApp::OnHelp() handler. This bypasses the default F1 OnHelp MFC code.

Go to this link for your reference https://learn.microsoft.com/en-us/cpp/mfc/reference/cwinapp-class?view=msvc-170

Do not hesitate to message us if you need further assistance.

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