Inno Setup Compiler “Cannot find the path specified” error with long paths

Question

I am using a .iss script to build an exe file inside Inno Setup Compiler. I need to package some node_modules into this application so I have a line under [Files] which looks like this:

Source: "{#SourcePath}Encore.Warehouse.UI\bin\Warehouse_Release\warehouse\*"; \
    DestDir: "{app}\warehouse"; Flags: ignoreversion recursesubdirs createallsubdirs

When I compile, I receive this error:

Here is the compiler output:

So, it appears to be running fine up until it aborted. My initial thought was that the browser.js doesn't exist but after double checking, this is not the case. Also, I'm using a wildcard in the source path so the compiler knows the file exists, but it seems to be having trouble compressing it.

One other thing that could be causing the issue is the file path length. Node modules usually end up having ridiculous file path lengths due to nested dependencies. In this case, the path length is 260. Assuming this is what's causing the problem, is there any way to get around it?

Answer 1

It's definitely due to a long path. Normally Windows applications cannot process paths longer than MAX_PATH (260 characters).
See Naming Files, Paths, and Namespaces on the MSDN.

A common workaround is prefixing the path with \\?\ (again see the MSDN article above). The prefix can be used for absolute paths only. But Inno Setup compiler chokes on that with the Source attribute. It looks for : and it accepts only path that either have a drive letter only before the : or that use compiler: or userdocs: prefixes.

You can hack that by using an UNC path with a volume ID (hence no colon).

Use the mountvol command to find the UNC path for your source drive.

And then you will have the same problem with a long path with the DestDir attribute, while installing (not when compiling). There, there's no problem with the colon, so you can simply use the \\?\ prefix.

Source: "\\?\Volume{bb919c3e-bdb1-42b8-9601-6715becd8683}\{#SourcePath}Encore.Warehouse.UI\bin\Warehouse_Release\warehouse\*"; \
    DestDir: "\\?\{app}\warehouse"; Flags: ignoreversion recursesubdirs createallsubdirs

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Of course, if the problem is caused by a root path being too long already, you can fix the problem simply be moving the source files to a folder with a shorter path. Or you can use subst to create a virtual drive or you can create a symlink/directory junction.