diff --git a/api/src/org/labkey/api/pipeline/PipeRoot.java b/api/src/org/labkey/api/pipeline/PipeRoot.java
index d71491f9586..850cc631b81 100644
--- a/api/src/org/labkey/api/pipeline/PipeRoot.java
+++ b/api/src/org/labkey/api/pipeline/PipeRoot.java
@@ -71,22 +71,22 @@ public interface PipeRoot extends SecurableResource
     Path resolveToNioPathFromUrl(String url);
 
     /**
-     * @return the file that's at the given relativePath from the pipeline root. Will be null if the relative path
-     * attempts to reference something that's not under the root (such as "../../etc/passwd". When the root
+     * @return the file that's at the given relativePath from the pipeline root. When the root
      * is configured with an alternative file path, we'll check to see if the file exists there. If not, we'll return
      * a path relative to the root's primary path.
+     * @throws org.labkey.api.util.FileUtil.InvalidPathReferenceException if the relative path
+     * attempts to reference something not under the root (such as "../../etc/passwd")
      */
     @Deprecated // prefer resolvePathToFileLike()
-    @Nullable
     File resolvePath(String relativePath);
 
     /**
-     * @return the file that's at the given relativePath from the pipeline root. Will be null if the relative path
-     * attempts to reference something that's not under the root (such as "../../etc/passwd". When the root
+     * @return the file that's at the given relativePath from the pipeline root. When the root
      * is configured with an alternative file path, we'll check to see if the file exists there. If not, we'll return
      * a path relative to the root's primary path.
+     * @throws org.labkey.api.util.FileUtil.InvalidPathReferenceException if the relative path
+     * attempts to reference something not under the root (such as "../../etc/passwd")
      */
-    @Nullable
     FileLike resolvePathToFileLike(String relativePath);
 
     /**
diff --git a/api/src/org/labkey/api/util/ExceptionUtil.java b/api/src/org/labkey/api/util/ExceptionUtil.java
index 6c623fe76c6..3649564a0ba 100644
--- a/api/src/org/labkey/api/util/ExceptionUtil.java
+++ b/api/src/org/labkey/api/util/ExceptionUtil.java
@@ -865,6 +865,21 @@ else if (ex instanceof BadRequestException)
             message = ex.getMessage();
             unhandledException = null;
         }
+        else if (ex instanceof FileUtil.InvalidPathReferenceException ipre)
+        {
+            responseStatus = HttpServletResponse.SC_NOT_FOUND;
+            errorType = ErrorRenderer.ErrorType.notFound;
+            if (ex.getMessage() != null)
+            {
+                message = ex.getMessage();
+                responseStatusMessage = message;
+            }
+            else
+                message = responseStatus + ": Page not Found";
+            unhandledException = null;
+            log.info("InvalidPathReferenceException: {}", ipre.getInput());
+            log.debug("InvalidPathReferenceException", ex);
+        }
         else if (ex instanceof NotFoundException)
         {
             responseStatus = HttpServletResponse.SC_NOT_FOUND;
diff --git a/api/src/org/labkey/api/util/FileUtil.java b/api/src/org/labkey/api/util/FileUtil.java
index d7675c3092d..d61983e5142 100644
--- a/api/src/org/labkey/api/util/FileUtil.java
+++ b/api/src/org/labkey/api/util/FileUtil.java
@@ -826,11 +826,20 @@ public static File appendPath(File dir, org.labkey.api.util.Path originalPath)
     {
         org.labkey.api.util.Path path = originalPath.normalize();
         if (path == null || (!path.isEmpty() && "..".equals(path.get(0))))
-            throw new InvalidPathException(originalPath.toString(), "Path to parent not allowed");
+            throw new InvalidPathReferenceException(originalPath.toString(), "Path to parent not allowed");
         @SuppressWarnings("SSBasedInspection")
         var ret = new File(dir, path.toString());
-        if (!ret.toPath().normalize().startsWith(dir.toPath().normalize()))
-            throw new InvalidPathException(originalPath.toString(), "Path to parent not allowed");
+        boolean valid;
+        try
+        {
+            valid = ret.toPath().normalize().startsWith(dir.toPath().normalize());
+        }
+        catch (InvalidPathException e)
+        {
+            throw new InvalidPathReferenceException(originalPath.toString(), e.getMessage());
+        }
+        if (!valid)
+            throw new InvalidPathReferenceException(originalPath.toString(), "Path to parent not allowed");
         return ret;
     }
 
@@ -840,7 +849,7 @@ public static FileLike appendPath(FileLike dir, org.labkey.api.util.Path path)
     {
         path = path.normalize();
         if (!path.isEmpty() && "..".equals(path.get(0)))
-            throw new InvalidPathException(path.toString(), "Path to parent not allowed");
+            throw new InvalidPathReferenceException(path.toString(), "Path to parent not allowed");
         return dir.resolveFile(path);
     }
 
@@ -871,7 +880,7 @@ public static File appendName(File dir, String name)
         var ret = new File(dir, name);
 
         if (!ret.toPath().normalize().startsWith(dir.toPath().normalize()))
-            throw new InvalidPathException(name, "Path to parent not allowed");
+            throw new InvalidPathReferenceException(name, "Path to parent not allowed");
         return ret;
     }
 
@@ -882,7 +891,7 @@ public static Path appendName(Path dir, String name)
         var ret = dir.resolve(name);
 
         if (!ret.normalize().startsWith(dir.normalize()))
-            throw new InvalidPathException(name, "Path to parent not allowed");
+            throw new InvalidPathReferenceException(name, "Path to parent not allowed");
         return ret;
     }
 
@@ -893,11 +902,24 @@ public static void legalPathPartThrow(String name)
     {
         int invalidCharacterIndex = StringUtils.indexOfAny(name, '/', File.separatorChar);
         if (invalidCharacterIndex >= 0)
-            throw new InvalidPathException(name, "Invalid file or directory name", invalidCharacterIndex);
+            throw new InvalidPathReferenceException(name, "Invalid file or directory name", invalidCharacterIndex);
         if (".".equals(name) || "..".equals(name))
-            throw new InvalidPathException(name, "Invalid file or directory name");
+            throw new InvalidPathReferenceException(name, "Invalid file or directory name");
     }
 
+    /** Our own subclass for bogus paths that we can special-case in ExceptionUtil in terms of HTTP response codes and logging */
+    public static class InvalidPathReferenceException extends InvalidPathException
+    {
+        public InvalidPathReferenceException(String path, String reason)
+        {
+            super(path, reason);
+        }
+
+        public InvalidPathReferenceException(String name, String reason, int index)
+        {
+            super(name, reason, index);
+        }
+    }
 
     public static String decodeSpaces(@NotNull String str)
     {
diff --git a/pipeline/src/org/labkey/pipeline/api/PipeRootImpl.java b/pipeline/src/org/labkey/pipeline/api/PipeRootImpl.java
index 51af9631832..b9069d2fd11 100644
--- a/pipeline/src/org/labkey/pipeline/api/PipeRootImpl.java
+++ b/pipeline/src/org/labkey/pipeline/api/PipeRootImpl.java
@@ -359,7 +359,6 @@ private Path findRootPath(Path file)
 
 
     @Override
-    @Nullable
     public File resolvePath(String pathStr)
     {
         if (null == pathStr)
@@ -370,7 +369,7 @@ public File resolvePath(String pathStr)
 
 
     @Nullable
-    public File resolvePath(org.labkey.api.util.Path path)
+    private File resolvePath(org.labkey.api.util.Path path)
     {
         var pair = _resolveRoot(path);
         if (null == pair)
@@ -380,8 +379,11 @@ public File resolvePath(org.labkey.api.util.Path path)
 
 
     @Override
-    public @Nullable FileLike resolvePathToFileLike(String relativePath)
+    public FileLike resolvePathToFileLike(String relativePath)
     {
+        if (null == relativePath)
+            throw new FileUtil.InvalidPathReferenceException(null, "Must specify a file path");
+
         var parsedPath = org.labkey.api.util.Path.parse(relativePath);
 
         var pair = _resolveRoot(parsedPath);