diff --git a/.changeset/fix-server-id-encoding.md b/.changeset/fix-server-id-encoding.md
new file mode 100644
index 000000000..8379b1e93
--- /dev/null
+++ b/.changeset/fix-server-id-encoding.md
@@ -0,0 +1,5 @@
+---
+"@solidjs/start": patch
+---
+
+fix: use percent encoding for `x-server-id` header value instead of reserved `#` character