diff --git a/packages/api/src/service-adapter.ts b/packages/api/src/service-adapter.ts
index c07bbf48..083c6563 100644
--- a/packages/api/src/service-adapter.ts
+++ b/packages/api/src/service-adapter.ts
@@ -33,6 +33,9 @@ export function toServiceCtx(ctx: AuthedContext): ServiceContext {
 export function toTRPCError(err: unknown): never {
   if (err instanceof TRPCError) throw err;
   if (err instanceof ZodError) {
+    // `onError` drops BAD_REQUEST, so this is the only trace of a ZodError
+    // thrown inside a service (e.g. an importer parsing a provider response).
+    console.warn("[trpc] ZodError thrown inside service:", err.issues);
     throw new TRPCError({
       code: "BAD_REQUEST",
       message: "Invalid input",