diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3f95acd22..9feacfe2f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,16 +13,18 @@ Item properties.
 ### Changed
 - Item `title` definition moved from core Item fields to [Common Metadata Basics](item-spec/common-metadata.md#basics) 
 fields. No change is required for STAC Items.
+- `putFeature` can return a `PreconditionFailed` to provide more explicit information when the resource has changed in the server
 
 ### Fixed
 - Fixed Item JSON Schema now `allOf` optional Common Metadata properties are evaluated.
 - Clarified usage of optional Common Metadata fields for STAC Items.
 
+
 ## [v0.9.0-rc1] - 2020-01-06
 
 ### Added
 - ItemCollection requires `stac_version` field, `stac_extensions` has also been added
-- A `description` field has been added to Item assets (also Asset definitions extension). 
+- A `description` field has been added to Item assets (also Asset definitions extension).
 - Field `mission` to [Common Metadata fields](item-spec/common-metadata.md).
 - Extensions:
     - [Version Indicators extension](extensions/version/README.md), adds `version` and `deprecated` fields to STAC Items and Collections
@@ -56,7 +58,8 @@ fields. No change is required for STAC Items.
     - Sort Extension - added non-JSON query/form parameter format
     - Fields extension has a simplified format for GET parameters
     - `search` extension renamed to `context` extension. JSON object renamed from `search:metadata` to `context`
-    - Query Extension - type restrictions on query predicates are more accurate, which may require additional implementation support. 
+    - Removed "next" from the search metadata and query parameter, added POST body and headers to the links for paging support
+    - Query Extension - type restrictions on query predicates are more accurate, which may require additional implementation support.
 
 ### Removed
 - `version` field in STAC Collections. Use [Version Extension](extensions/version/README.md) instead
diff --git a/api-spec/STAC-extensions.yaml b/api-spec/STAC-extensions.yaml
index d0ceefb43..18db5756f 100644
--- a/api-spec/STAC-extensions.yaml
+++ b/api-spec/STAC-extensions.yaml
@@ -226,6 +226,8 @@ paths:
           $ref: '#/components/responses/BadRequest'
         '404':
           $ref: '#/components/responses/NotFound'
+        '412':
+          $ref: '#/components/responses/PreconditionFailed'
         5XX:
           $ref: '#/components/responses/InternalServerError'
         default:
@@ -240,7 +242,7 @@ paths:
     patch:
       summary: update an existing feature by Id with a partial item definition
       description: >-
-        Use this method to update an existing feature. Requires a GeoJSON 
+        Use this method to update an existing feature. Requires a GeoJSON
         fragement (containing the fields to be updated) be submitted.
       operationId: patchFeature
       tags:
@@ -2318,6 +2320,12 @@ components:
         application/json:
           schema:
             $ref: '#/components/schemas/exception'
+    PreconditionFailed:
+      description: Some condition specified by the request could not be met in the server
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/exception'
     InternalServerError:
       description: >-
         The request was syntactically and semantically valid, but an error
diff --git a/api-spec/extensions/transaction/transaction.fragment.yaml b/api-spec/extensions/transaction/transaction.fragment.yaml
index 9c519c723..683ce974e 100644
--- a/api-spec/extensions/transaction/transaction.fragment.yaml
+++ b/api-spec/extensions/transaction/transaction.fragment.yaml
@@ -94,6 +94,8 @@ paths:
           $ref: '#/components/responses/BadRequest'
         '404':
           $ref: '#/components/responses/NotFound'
+        '412':
+          $ref: '#/components/responses/PreconditionFailed'
         '5XX':
           $ref: '#/components/responses/InternalServerError'
         default:
@@ -108,7 +110,7 @@ paths:
     patch:
       summary: update an existing feature by Id with a partial item definition
       description: >-
-        Use this method to update an existing feature. Requires a GeoJSON 
+        Use this method to update an existing feature. Requires a GeoJSON
         fragement (containing the fields to be updated) be submitted.
       operationId: patchFeature
       tags:
@@ -247,6 +249,12 @@ components:
         application/json:
           schema:
             $ref: '#/components/schemas/exception'
+    PreconditionFailed:
+      description: Some condition specified by the request could not be met in the server
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/exception'
     InternalServerError:
       description: The request was syntactically and semantically valid, but an error occurred while trying to act upon it
       content: