I was running into this too. I noticed that Gatsby seems to be dead and while in the long run, I expect to move away from Gatsby, but in the short-term, I needed a fix.

Issue

It seems like the source of the bug is in gatsby-link, where several code paths don't call withPrefix. I cloned the gatsby repo, and modified the gatsby-link package to add the appropriate lines. (Confusingly, this file seems to have an isAbsolutePath function which returns true for relative paths).

diff --git a/packages/gatsby-link/src/rewrite-link-path.js b/packages/gatsby-link/src/rewrite-link-path.js
index e1b2b49671..6668b76c9b 100644
--- a/packages/gatsby-link/src/rewrite-link-path.js
+++ b/packages/gatsby-link/src/rewrite-link-path.js
@@ -13,25 +13,26 @@ const getGlobalTrailingSlash = () =>
 function applyTrailingSlashOptionOnPathnameOnly(path, option) {
   const { pathname, search, hash } = parsePath(path)
   const output = applyTrailingSlashOption(pathname, option)
 
   return `${output}${search}${hash}`
 }
 
 function absolutify(path, current) {
   // If it's already absolute, return as-is
   if (isAbsolutePath(path)) {
-    return path
+    return withPrefix(path)
   }
 
+  const prefixed = withPrefix(path)
   const option = getGlobalTrailingSlash()
-  const absolutePath = resolve(path, current)
+  const absolutePath = resolve(prefixed, current)
 
   if (option === `always` || option === `never`) {
     return applyTrailingSlashOptionOnPathnameOnly(absolutePath, option)
   }
 
   return absolutePath
 }
 
 function applyPrefix(path) {
   const prefixed = withPrefix(path)

Fixing It

The site I'm working on uses patch-package to apply the above change to Gatsby link. To generate this yourself, you can clone the repo, apply the above change, build, and then generate a patch from that.

If you'd rather re-use my work, you can copy the patch file in this gist to patches/gatsby-link+5.10.0.patch in your repository.

I haven't tested this too thoroughly, but it seems to handle all the cases I've thrown at it so far.

Thank you for sharing your solution with the community @rosszurowski!

Though we aren't actively investing in new features or low-priority bug fixes, Gatsby is still maintained.

If you open a PR with your bug fix, we'll take a look and get it merged so everyone can benefit! Thanks 🙂

Hi @serhalp — good to know! I didn't see an official response in that thread, so assumed it was accurate. I'll gladly open a PR with the fix.

Awesome, thank you!

For the record, there is a response here and a blog post here.