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+---
+layout: post
+title: "Fix: macOS 15 Sequoia CUPS printing fails with Validate-Job client-error-not-found"
+date: 2026-03-08
+tags: [macos, cups, printing, linux]
+---
+
+When adding a remote CUPS print server on macOS 15 Sequoia, print jobs may fail immediately with:
+
+```
+Validate-Job client-error-not-found
+```
+
+## Cause
+
+macOS sends a `Validate-Job` IPP request before submitting the actual print job. If the queue URI is incorrect, the server cannot find the printer and rejects it with this error.
+
+The most common culprit is the **queue name** field when adding the printer via System Settings → Printers & Scanners → Add Printer → IP tab. Leaving it blank or entering just the printer name causes macOS to target the wrong IPP endpoint.
+
+## Fix
+
+When adding the printer, set the **Queue** field to:
+
+```
+/printers/<printername>
+```
+
+(note `/printers/` prefix, it's not **just the CUPS queue name**)
+
+For example, if your printer is named `office-laser`:
+
+```
+/printers/office-laser
+```
+
+The full URI should resolve to:
+
+```
+ipp://<server>:631/printers/<printername>
+```
+
+## Fixing an already-added printer
+
+No need to remove and re-add it. Update the URI in place with `lpadmin`:
+
+```bash
+lpadmin -p <printername> -v ipp://<server>:631/printers/<printername>
+```
+
+## Verifying the correct URI
+
+You can confirm the printer name and path on the CUPS server with:
+
+```bash
+lpstat -v
+```
+
+And test the endpoint directly from the Mac before adding the printer:
+
+```bash
+ipptool -tv ipp://<server>:631/printers/<printername> get-printer-attributes.test
+```