microsoft/aspire · error · JsonException

JSON Patch operation

Error message

JSON Patch operation '{operation}' is not supported.

What it means

JsonPatch.ApplyOperation supports only the RFC 6902 operations 'add', 'remove', and 'replace'. Any other 'op' value — including valid RFC 6902 ops like 'move', 'copy', and 'test', which this minimal implementation deliberately does not support — throws a JsonException.

Solutions

1. Rewrite 'move' as a 'remove' + 'add' pair of operations.
2. Rewrite 'copy' as an explicit 'add' carrying the copied value.
3. Remove 'test' operations or implement pre-checks in the patch producer.
4. Fix misspelled op names to one of 'add', 'remove', 'replace'.

Example fix

// before
[ { "op": "move", "from": "/a/b", "path": "/a/c" } ]
// after
[ { "op": "remove", "path": "/a/b" }, { "op": "add", "path": "/a/c", "value": <movedValue> } ]

var allowedOps = new HashSet<string> { "add", "remove", "replace" };
bool AllOpsSupported(JsonNode patch) =>
    patch.AsArray().All(op => op["op"]!.GetValue<string>() is string s && allowedOps.Contains(s));

try { patch.Apply(target); }
catch (JsonException ex) when (ex.Message.Contains("is not supported"))
{
    logger.LogError(ex, "Unsupported JSON Patch op: {Message}", ex.Message);
    // rewrite move/copy/test ops or fail the update
}

When it happens

Trigger: Applying a patch document containing { "op": "move" }, { "op": "copy" }, { "op": "test" }, or a misspelled op such as 'update' through the DCP resource update path.

Common situations: Patches generated by generic JSON Patch libraries that emit the full RFC 6902 op set; hand-written patches using 'move'/'copy' for convenience; drift between a producer updated for RFC completeness and Aspire's minimal applier.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• A JSON Patch operation must contain string 'op' and 'path'…
• JSON Patch operation
• Service resources do not consume any services
• Service resources do not produce any services
• A JSON Patch path can only traverse objects and arrays.

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/3f9947b24ebdc45c. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting/Dcp/JsonPatch.cs:183

                throw new JsonException($"JSON Pointer segment '{segment}' ends with an incomplete escape.");
            }

            result.Append(segment[index] switch
            {
                '0' => '~',
                '1' => '/',
                _ => throw new JsonException($"JSON Pointer segment '{segment}' contains an invalid escape."),
            });
        }

        return result.ToString();
    }

    private static JsonNode? ApplyOperation(JsonNode? current, string operation, string[] segments, bool hasValue, JsonNode? value)
    {
        if (operation is not ("add" or "remove" or "replace"))
        {
            throw new JsonException($"JSON Patch operation '{operation}' is not supported.");
        }

        if (operation is not "remove" && !hasValue)
        {
            throw new JsonException($"JSON Patch operation '{operation}' requires a 'value' property.");
        }

        if (segments.Length == 0)
        {
            return operation switch
            {
                "remove" => null,
                _ => value?.DeepClone(),
            };
        }

        var parent = GetParent(current, segments);
        var finalSegment = segments[^1];

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