# A039 – Non-ASCII filename characters replaced with question marks

**URL:** <https://developer.community.nhs.uk/t/a039-non-ascii-filename-characters-replaced-with-question-marks/16218>\
**Category:** e-Referral Service (e-RS)\
**Tags:** testing, fhir\
**Created:** [3 November 2026 09:29 UTC](https://developer.community.nhs.uk/t/a039-non-ascii-filename-characters-replaced-with-question-marks/16218 "2026-11-03T09:29:08Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![jose.ruiz.ruiz](https://avatars.discourse-cdn.com/v4/letter/j/c4cdca/32.png) [@jose.ruiz.ruiz](https://developer.community.nhs.uk/u/jose.ruiz.ruiz)\
**Post date:** [3 November 2026 09:29 UTC](https://developer.community.nhs.uk/t/a039-non-ascii-filename-characters-replaced-with-question-marks/16218/1 "2026-11-03T09:29:08Z")

</div>

Hello NHS e-RS API team,

We are testing **A039 – Upload file to document store (FHIR R4)** in the integration environment and have found that accented characters in `NHSD-eRS-File-Name` are not preserved.

```auto
POST https://int.api.service.nhs.uk/referrals/FHIR/R4/Binary

```

We reproduced this independently of our application using backend CURL. For the UTF-8 test, the outgoing hexadecimal trace confirms that `é` was transmitted correctly as bytes `C3 A9`.

Our findings are:

| Filename header supplied | Returned filename |
| --- | --- |
| `filenamé-test.txt`, using UTF-8 bytes `C3 A9` | `filenam??-test.txt` |
| `filenamé-test.txt`, using Latin-1 byte `E9` | `filenam?-test.txt` |
| `filenam%C3%A9-test.txt`, using percent-encoded UTF-8 | Literal `filenam%C3%A9-test.txt` |

For example, the UTF-8 request returned:

```auto
Content-Disposition: attachment; filename="=?UTF-8?Q?filenam=3F=3F-test-3.txt?="; filename*=UTF-8''filenam%3F%3F-test-3.txt

```

The replacement characters are already present in the **A039 response, before the storage PUT**. We have also observed corrupted filenames in the e-RS Professional Web App after uploading and associating attachments.

Could you please confirm the supported encoding for non-ASCII filenames in `NHSD-eRS-File-Name`?

Request details for tracing:

```auto
Environment: Integration
Request timestamp, including timezone: Tue, 03 Nov 2026 09:01:34 GMT
X-Correlation-ID: 7f87b8f5-7d5f-4f79-9c32-616f64361a58
Returned X-Request-ID: 61dc20e7-91d6-44d4-b59e-e728d2e68c74-1
Application ID: 6a0392f2-ba38-413f-b83c-449ec1168b5a

```

Many thanks.

Jose