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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(201.6, 1%, 29%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EA%3C/text%3E%3C/svg%3E)
System.Windows.Forms.Help.ShowHelp(null, helpFile, HelpNavigator.TopicId, helpId);
I have to use
ShellExecute(IntPtr.Zero, new StringBuilder("Open"), new StringBuilder(helpFile), null, null, 1);
But can not goto topic Page.
Office 365 is also fail.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(176, 33%, 27%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EJH%3C/text%3E%3C/svg%3E)
We're having the same problem, see https://learn.microsoft.com/en-us/answers/questions/308412/is-the-latest-version-of-excel-365-blocking-htmlhe.html
ShellExecute will work as Excel cannot block the call to the HtmlHelp API, but that is not a solution for us unfortunately.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(185.6, 55.00000000000001%, 27%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EJ%3C/text%3E%3C/svg%3E)
The same problem here!
Is it a "bad" Office update? Or Windows? Are there any plans to fix it?
I hesitate to use ShellExecute ( ) for the same reason - can not open a particular topic.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(12.8, 15%, 11%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EAR%3C/text%3E%3C/svg%3E)
Running into this too. Running as a process and using the mapid argument seems to work for now.
// Used to be Help.ShowHelp(parentForm, pathToHelpFile, HelpNavigator.TopicId, myContextId)
Process.Start("hh.exe", $"-mapid {myContextId} my-helpfile.chm");
Should I be looking for an alternative to CHM for this add-in in-case they block the process? Maybe display HTML in a task pane instead?
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(265.6, 33%, 35%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EGV%3C/text%3E%3C/svg%3E)
In Excel, at least, it might be worth trying to call Application.Help instead.
Thanks, but I hesitate to use Application.Help .
Every time Help is called from the application, Application.Help opens a new Help window.
And when user closes the application, he has to close all Help windows manually.
HtmlHelp () doesn't have these issues.
Call HtmlHelp(0, ....HelpName, &H12, 0) closes help file automatically
Ah - that is a side-effect I wasn't aware of.