diff --git a/csv-table-hub-main/src/__tests__/stored-row-errors.test.tsx b/csv-table-hub-main/src/__tests__/stored-row-errors.test.tsx
new file mode 100644
index 0000000..2b526d6
--- /dev/null
+++ b/csv-table-hub-main/src/__tests__/stored-row-errors.test.tsx
@@ -0,0 +1,46 @@
+// M3c (#107): the Migrated files Preview shows why rows failed, read from the server.
+
+import { afterEach, expect, it, vi } from "vitest";
+import { render, screen } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import { StoredRowErrors } from "@/routes/_authenticated/index";
+
+const detail = {
+  id: "7",
+  status: "partly_imported",
+  fileName: "people.csv",
+  uploader: "alice",
+  failedRows: 1,
+  rowErrors: [{ rowNumber: 2, column: "n", value: "x", reason: '"x" is not a whole number' }],
+  logs: [],
+};
+
+function show(body: unknown) {
+  const fetchMock = vi
+    .fn()
+    .mockResolvedValue(
+      new Response(JSON.stringify(body), { headers: { "content-type": "application/json" } }),
+    );
+  vi.stubGlobal("fetch", fetchMock);
+  const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+  render(
+    <QueryClientProvider client={client}>
+      <StoredRowErrors uploadId="7" fileName="people.csv" />
+    </QueryClientProvider>,
+  );
+  return fetchMock;
+}
+
+afterEach(() => vi.unstubAllGlobals());
+
+it("lists the stored reasons from the upload's server record", async () => {
+  const fetchMock = show(detail);
+  expect(await screen.findByText('"x" is not a whole number')).toBeInTheDocument();
+  expect(screen.getByRole("button", { name: /error report/i })).toBeInTheDocument();
+  expect(String(fetchMock.mock.calls[0][0])).toMatch(/\/api\/csv\/uploads\/7$/);
+});
+
+it("says so when no reasons were stored", async () => {
+  show({ ...detail, rowErrors: [] });
+  expect(await screen.findByText(/no failure reasons were stored/i)).toBeInTheDocument();
+});
diff --git a/csv-table-hub-main/src/lib/csv.functions.ts b/csv-table-hub-main/src/lib/csv.functions.ts
index d073be8..cd6c603 100644
--- a/csv-table-hub-main/src/lib/csv.functions.ts
+++ b/csv-table-hub-main/src/lib/csv.functions.ts
@@ -89,6 +89,8 @@ const csvFileSummarySchema = z.object({
   row_count: z.number(),
   total_rows: z.number().nullable().optional(),
   failed_rows: z.number().nullable().optional(),
+  uploader: z.string().nullable().optional(),
+  upload_id: z.string().nullable().optional(),
   column_names: z.array(z.string()),
   created_at: z.string(),
 });
@@ -231,3 +233,19 @@ export async function previewCsvTable(
     previewRowsSchema,
   );
 }
+
+// M3c (#107): an upload's failure reasons and step log, stored on the server.
+const uploadDetailSchema = z.object({
+  id: z.string(),
+  status: z.string(),
+  fileName: z.string(),
+  uploader: z.string().nullable(),
+  failedRows: z.number().nullable(),
+  rowErrors: z.array(rowErrorSchema).nullable(),
+  logs: z.array(processingLogSchema).nullable(),
+});
+export type UploadDetail = z.infer<typeof uploadDetailSchema>;
+
+export async function getUploadDetail(uploadId: string): Promise<UploadDetail> {
+  return apiFetch(`/api/csv/uploads/${encodeURIComponent(uploadId)}`, uploadDetailSchema);
+}
diff --git a/csv-table-hub-main/src/routes/_authenticated/index.tsx b/csv-table-hub-main/src/routes/_authenticated/index.tsx
index cfc995a..ae1a1af 100644
--- a/csv-table-hub-main/src/routes/_authenticated/index.tsx
+++ b/csv-table-hub-main/src/routes/_authenticated/index.tsx
@@ -23,7 +23,7 @@ import { createFileRoute, Link, useRouter } from "@tanstack/react-router";
 import { useQuery, useSuspenseQuery } from "@tanstack/react-query";
 import { useCallback, useEffect, useRef, useState, type ReactNode } from "react";
 import {
-  filesQuery, loadFiles, previewCsvTable, previewCsv, listTeTables, uploadCsv,
+  filesQuery, loadFiles, previewCsvTable, getUploadDetail, previewCsv, listTeTables, uploadCsv,
   type CsvFileSummary, type ColumnType, type TeTableInfo,
 } from "@/lib/csv.functions";
 import { parseCsvPreview, COLUMN_TYPE_LABEL, sanitizeColumns, type CsvPreview } from "@/lib/csv-preview";
@@ -743,6 +743,28 @@ function PreviewTable({file}:{file:CsvFileSummary}){
         </TableBody>
       </Table>
       <p className="p-2 text-xs text-muted-foreground">Showing up to 50 rows. Table has {file.row_count} row{file.row_count===1?"":"s"} total.{failedRowsNote(file)&&<span className="text-destructive"> {failedRowsNote(file)} validation and weren't imported.</span>}</p>
+      {file.upload_id&&(file.failed_rows??0)>0&&<StoredRowErrors uploadId={file.upload_id} fileName={file.file_name}/>}
+    </div>
+  );
+}
+
+// M3c (#107): why rows failed, read from the server, so every user in the tenant sees the same reasons.
+export function StoredRowErrors({uploadId,fileName}:{uploadId:string;fileName:string}){
+  const {data,isLoading,error}=useQuery({queryKey:["upload-detail",uploadId],queryFn:()=>getUploadDetail(uploadId)});
+  if(isLoading)return<p className="p-2 text-xs text-muted-foreground">Loading failure reasons…</p>;
+  if(error)return<p className="p-2 text-xs text-destructive">{(error as Error).message}</p>;
+  const errors=data?.rowErrors??[];
+  if(errors.length===0)return<p className="p-2 text-xs text-muted-foreground">No failure reasons were stored for this upload.</p>;
+  return (
+    <div className="border-t">
+      <div className="flex items-center justify-between p-2">
+        <p className="text-xs font-medium">Rows that failed{(data?.failedRows??0)>errors.length&&` (first ${errors.length} of ${data?.failedRows})`}</p>
+        <Button size="sm" variant="outline" className="h-7" onClick={()=>downloadErrorReport(fileName,buildErrorRows(fileName,errors),"csv")}><Download className="mr-1 h-3.5 w-3.5"/>Error report</Button>
+      </div>
+      <Table>
+        <TableHeader><TableRow><TableHead>Row</TableHead><TableHead>Column</TableHead><TableHead>Value</TableHead><TableHead>Reason</TableHead></TableRow></TableHeader>
+        <TableBody>{errors.slice(0,50).map((re,i)=><TableRow key={i}><TableCell className="tabular-nums text-xs">{re.rowNumber}</TableCell><TableCell className="text-xs">{re.column??"—"}</TableCell><TableCell className="max-w-[180px] truncate font-mono text-xs">{re.value??"—"}</TableCell><TableCell className="text-xs text-destructive">{re.reason}</TableCell></TableRow>)}</TableBody>
+      </Table>
     </div>
   );
 }