Using SetVirtualHostNameToFolderMapping with WebView2 allows you to map a virutal host name to a folder path. This is like an excellent way to preview content but at present it doesn't support long file paths on Windows - this repo is a quick test/demonstration of that created in part to help me confirm all the details.
In the issue filed for this - Long File Paths result in Broken Content when using SetVirtualHostNameToFolderMapping · Issue #1573 · MicrosoftEdge/WebView2Feedback · GitHub - @champnic noted that "This is a known limitation currently of file loading, and I believe it also affects Microsoft Edge and Chromium. I'll open this bug on our backlog, but in full transparency it's likely to be lower priority for us."
To check this repo out on Windows you will have to set the core.longpaths true HOWEVER you might want to see git/core.txt at d003d728ffa6c0006da875ec6318d3f6b28a4ddb · git-for-windows/git for some potential downfalls. (If you are using GitHub Desktop and having problems try running 'git config --global core.longpaths true' - I found the sometimes recommended '--system' did not help.) (As an aside for me this repo was eye opening in regards to the current default support for long file paths in Windows, File Explorer, Git, GitHub Desktop and Visual Studio - if you haven't run into this issue just trying to check out this repo might be interesting...)
Directly related to this issues are Maximum Path Length Limitation - Win32 apps | Microsoft Docs and Naming Files, Paths, and Namespaces - Win32 apps | Microsoft Docs.
I did try a few other things before creating an Issue, none of which had any impact on the problem:
- Use group policy to enable the newer Win10 behavior that removes the MAX_PATH limitations -> Computer Configuration > Administrative Templates > System > Filesystem > Enable Win32 long paths.
- Use the \\?\ prefix in the call to SetVirtualHostNameToFolderMapping
- Add an application manifest with:
<application xmlns="urn:schemas-microsoft-com:asm.v3">
<windowsSettings xmlns:ws2="http://schemas.microsoft.com/SMI/2016/WindowsSettings">
<ws2:longPathAware>true</ws2:longPathAware>
</windowsSettings>
</application>
The screen shot above is from the sample app and shows:
- In the top panel the source is set to an html file that is below MAX_PATH value and loads, but the top image is a link to a file beyond the MAX_PATH - the error is: Failed to load resource: net::ERR_ACCESS_DENIED (the top panel also includes some other working content as a sanity check)
- In the bottom panel the source is set to a file with a long enough name to be over the MAX_PATH and it fails to load