Can you keep using it?
Can you keep using it?
Contact customer support if any of these apply
- !The message remains even when the settings and loaded paper clearly match.
- !The printer no longer saves tray or duplex settings correctly.
What to check first
Step-by-step checks
- 1
Consumable check
Check the loaded paper size and the tray setting on the printer.
Start with the official recovery step before moving on to parts or deeper servicing.
- 2
Consumable check
Compare the driver job settings with the paper actually loaded.
- 3
Safe first step
Retry the job once the media size and duplex settings agree.
Background
What this message usually means
Brother shows Size Error DX or Size Error 2-sided when the machine cannot continue a duplex job because the loaded media size or duplex setup does not match what the printer expects. It is usually a media-setting mismatch rather than a mechanical fault.
Before the message
What users usually notice first
Messages like this often appear after the printer fails one of its normal startup, supply, or paper-path checks and cannot return to ready state cleanly.
Diagnosis
Likely causes
The loaded paper size does not match the duplex job.
The tray settings are wrong for the media currently loaded.
The printer is trying to duplex a size or source that is not configured correctly.
Service
When service or replacement is more likely
- -This is a setup mismatch, not a paper jam.
Avoid wrong turns
Common misreads of this message
- -Treating the message like a confirmed failed part instead of a support clue about which system has stopped the printer.
- -Assuming no physical path issue exists just because no full sheet is visible at first glance.
See also
Related codes in this family
Explore more
More Brother printer families
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Helpful guides for this problem
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When a printer says paper jam but there isn't one
What a false paper-jam warning usually points to, from hidden scraps and tray issues to faults that are no longer simple jams.
Guide
Common Brother printer messages that usually mean stop and check support
The Brother messages that usually mean it is time to stop retrying and treat the fault more seriously.
Guide
How to tell if a printer fault is a cartridge issue or a service issue
How to separate ordinary cartridge or toner trouble from the kind of printer fault that usually points to real service.
Boundary
When to stop troubleshooting and move to support
Use the message once to classify the problem, then move to support if the printer still cannot return to ready after the first safe checks.
Keep browsing
Where to go next
Source notes
Brother's HL-L5210DN error-message list includes Size Error DX and Size Error 2-sided among the LCD stop messages.
Built around Brother HL-L5210DN-class official error-message guidance. Exact wording can vary by regional firmware and closely related office-laser variants.
Printer error codes can vary a little by firmware, region, and exact model variant. Use this guide as a family-level starting point and stop if the next step would require disassembly or service-mode changes.
Known family variants: HL-L5210DN, HL-L5210DW
Last reviewed: 2026-04-12
Reference: Open reference