quarkusio/quarkus · error · RuntimeException

Cannot deserialize data for data-content-encoding: '${dataCo

Error message

Cannot deserialize data for data-content-encoding: '${dataContentEncoding}'.

What it means

JsonCloudEventImpl.data() deserializes the event's JSON payload. If the JSON contains a 'datacontentencoding' attribute with any value other than 'base64', it cannot handle it and throws a RuntimeException naming the encoding.

Source

Thrown at extensions/funqy/funqy-knative-events/runtime/src/main/java/io/quarkus/funqy/runtime/bindings/knative/events/JsonCloudEventImpl.java:191

    @Override
    public T data() {
        if (data != null) {
            return data;
        }
        if ((dataContentType() == null || dataContentType().startsWith("application/json")) && !byte[].class.equals(dataType)) {
            data = reader.readValue(event.get("data"));
            return data;
        } else if (byte[].class.equals(dataType)) {
            try {
                if (majorSpecVersion() == 0) {
                    boolean isBase64 = false;
                    if (event.has("datacontentencoding")) {
                        String dce = event.get("datacontentencoding").asText();
                        if ("base64".equals(dce)) {
                            isBase64 = true;
                        } else {
                            throw new RuntimeException("Cannot deserialize data for data-content-encoding: '" + dce + "'.");
                        }
                    }
                    if (isBase64) {
                        if (event.has("data")) {
                            String txt = event.get("data").asText();
                            data = (T) Base64.getDecoder().decode(txt);
                            return data;
                        } else {
                            return null;
                        }
                    } else {
                        if (event.has("data")) {
                            data = (T) mapper.writeValueAsBytes(event.get("data"));
                            return data;
                        } else {
                            return null;
                        }
                    }

View on GitHub (pinned to e1c734241f)

Solutions

Re-publish the event without the datacontentencoding attribute or with 'base64'.
Preprocess the event JSON to remove/normalize the datacontentencoding field before it reaches the binding.
Handle the RuntimeException and fall back to manual decoding of the data field.
Upgrade the event source to CloudEvents 1.0, where datacontentencoding was removed.

Example fix

// before
{"specversion":"1.0","datacontentencoding":"binary","data":"..."}
// after
{"specversion":"1.0","data":"..."}

Defensive patterns

Strategy: validation

Validate before calling

JsonNode dce = event.get("datacontentencoding");
if (dce != null && !"base64".equals(dce.asText())) {
    throw new IllegalArgumentException("Unsupported datacontentencoding: " + dce.asText());
}

Type guard

boolean isSupportedEncoding(JsonNode event) { JsonNode n = event.get("datacontentencoding"); return n == null || "base64".equals(n.asText()); }

Try / catch

try { data = event.data(dataType); } catch (RuntimeException e) { if (e.getMessage().contains("data-content-encoding")) { data = manualDecode(event.get("data").asText()); } else throw e; }

Prevention

Publish events without datacontentencoding (removed in CloudEvents 1.0)
Normalize incoming event JSON to strip legacy encoding fields
Handle base64 only, decode manually otherwise
Update legacy event sources (e.g. old SendGrid webhooks) to spec 1.0

When it happens

Trigger: Parsing a JSON-serialized CloudEvent whose datacontentencoding is e.g. 'binary', 'utf-8', or any non-base64 string; the code only special-cases 'base64' and throws otherwise.

Common situations: Event producers (older SendGrid, custom brokers) set datacontentencoding to values from the 0.1 spec era that modern CloudEvents dropped; hand-crafted event JSON with unexpected fields.

Related errors

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/d73d14d44781af2b. Report an issue: GitHub.