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+# ADR - Error model
+
+This ADR must determine if we must use the standard TMF way for error model
+or use the universal way: [RFC 7807](https://tools.ietf.org/html/rfc7807).
+
+## Considered Options
+
+1. TMF way
+2. RFC 7807 - Problem Details for HTTP APIs
+
+## Pros and Cons of the Options
+
+### TMF way
+
+* Good, because it is the TMF way.
+* Bad, because it is not the universal way.
+* Bad, because it is not natively supported by frameworks.
+* Bad, because it can not be used for array of errors.
+
+example:
+
+```json
+{
+  "code": "42",
+  "reason": "The answer to life, the universe and everything.",
+  "message": "The answer to life, the universe and everything.",
+  "status": "500",
+  "referenceError": "https://en.wikipedia.org/wiki/The_Hitchhiker%27s_Guide_to_the_Galaxy"
+}
+```
+
+validation example:
+
+```json
+{
+  "code": "400-1",
+  "reason": "Your request parameters didn't validate.",
+  "message": "Name is required.",
+  "status": "400",
+  "referenceError": "https://example.net/validation-error/name",
+}
+```
+
+### RFC 7807 - Problem Details for HTTP APIs
+
+* Good, because it is the universal way.
+* Good, because it is natively supported by lots of frameworks.
+* Good, because it can be used for array of errors.
+* Good, because the error use a specific type (`application/problem+json`)
+  which can be used for content negotiation.
+* Bad, because it is not the TMF way.
+
+example:
+
+```json
+{
+  "type": "https://en.wikipedia.org/wiki/The_Hitchhiker%27s_Guide_to_the_Galaxy",
+  "title": "The answer to life, the universe and everything.",
+  "detail": "42"
+}
+```
+
+validation example:
+
+```json
+{
+  "type": "https://example.net/validation-error",
+  "title": "Your request parameters didn't validate.",
+  "errors": [
+    {
+      "path": "name",
+      "message": "Name is required."
+    },
+    {
+      "path": "address.street",
+      "message": "Street must be at least 5 characters long."
+    }
+  ]
+}
+```
+
+## Decision Outcome
+
+The solution must be used for all INTEROP protocols.
+
+## Positive Consequences
+
+TODO
+
+## Negative Consequences
+
+TODO