diff --git a/CHANGELOG.md b/CHANGELOG.md
index a5f9518c72..7dd0518396 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,22 @@
+## 1.2.1-rc.3
+
+>**Note:** If your Gen 3 device does not have a Cloud connection, it is recommended to update system firmware, and then the bootloader via CLI with `particle flash --serial bootloader.bin` (bootloaders found in Github release)
+>
+>This release contains v311 bootloaders.
+
+### ENHANCEMENTS
+
+- Cache cellular diagnostics [#1820](https://github.com/particle-iot/device-os/pull/1820)
+- allow the bootloader to be flashed over DFU [#1788](https://github.com/particle-iot/device-os/pull/1788)
+
+### BUG FIXES
+
+- Add two-digit mnc diagnostic flag [#1804](https://github.com/particle-iot/device-os/pull/1804)
+- [lte] cellular fixes [#1824](https://github.com/particle-iot/device-os/pull/1824)
+- fixes #1811 - increases the number of event handlers to 6 [#1822](https://github.com/particle-iot/device-os/pull/1822)
+- [gen 3] fixes memory usage diagnostics (reported negative values in safe mode) [#1819](https://github.com/particle-iot/device-os/pull/1819)
+- System.disableUpdates() operates asynchronously [#1801](https://github.com/particle-iot/device-os/pull/1801)
+
 ## 1.2.1-rc.2
 
 >**Note:** If your Gen 3 device does not have a Cloud connection, it is recommended to update system firmware, and then the bootloader via CLI with `particle flash --serial bootloader.bin` (bootloaders found in Github release)
diff --git a/build/release.sh b/build/release.sh
index ccbb6ccfe7..5a4105757f 100755
--- a/build/release.sh
+++ b/build/release.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 set -o errexit -o pipefail -o noclobber -o nounset
 
-VERSION="1.2.1-rc.2"
+VERSION="1.2.1-rc.3"
 
 function display_help ()
 {
diff --git a/build/version.mk b/build/version.mk
index f82e61665d..5240e22e08 100755
--- a/build/version.mk
+++ b/build/version.mk
@@ -1,7 +1,7 @@
-VERSION_STRING = 1.2.1-rc.2
+VERSION_STRING = 1.2.1-rc.3
 
 # PRODUCT_FIRMWARE_VERSION reported by default
 # FIXME: Unclear if this is used, PRODUCT_FIRMWARE_VERSION defaults to 65535 every release
-VERSION = 1211
+VERSION = 1212
 
 CFLAGS += -DSYSTEM_VERSION_STRING=$(VERSION_STRING)
diff --git a/modules/shared/system_module_version.mk b/modules/shared/system_module_version.mk
index 6dae903d9d..4f09294883 100644
--- a/modules/shared/system_module_version.mk
+++ b/modules/shared/system_module_version.mk
@@ -1,6 +1,6 @@
 # Skip to next 100 every v0.x.0 release (e.g. 108 for v0.6.2 to 200 for v0.7.0-rc.1)
 # Bump by 1 for every prerelease or release with the same v0.x.* base.
-COMMON_MODULE_VERSION ?= 1211
+COMMON_MODULE_VERSION ?= 1212
 SYSTEM_PART1_MODULE_VERSION ?= $(COMMON_MODULE_VERSION)
 SYSTEM_PART2_MODULE_VERSION ?= $(COMMON_MODULE_VERSION)
 SYSTEM_PART3_MODULE_VERSION ?= $(COMMON_MODULE_VERSION)
diff --git a/system/inc/system_version.h b/system/inc/system_version.h
index 4d8510df7d..328c3c2aa1 100644
--- a/system/inc/system_version.h
+++ b/system/inc/system_version.h
@@ -128,7 +128,8 @@ extern "C" {
 #define SYSTEM_VERSION_v120RC1        SYSTEM_VERSION_RC(1, 2, 0, 1)
 #define SYSTEM_VERSION_v121RC1        SYSTEM_VERSION_RC(1, 2, 1, 1)
 #define SYSTEM_VERSION_v121RC2        SYSTEM_VERSION_RC(1, 2, 1, 2)
-#define SYSTEM_VERSION SYSTEM_VERSION_v121RC2
+#define SYSTEM_VERSION_v121RC3        SYSTEM_VERSION_RC(1, 2, 1, 3)
+#define SYSTEM_VERSION SYSTEM_VERSION_v121RC3
 
 /**
  * Previously we would set the least significant byte to 0 for the final release, but to make
@@ -221,6 +222,7 @@ extern "C" {
 #define SYSTEM_VERSION_120RC1
 #define SYSTEM_VERSION_121RC1
 #define SYSTEM_VERSION_121RC2
+#define SYSTEM_VERSION_121RC3
 
 typedef struct __attribute__((packed)) SystemVersionInfo
 {
diff --git a/system/system-versions.md b/system/system-versions.md
index 5f024104bb..264b773f38 100644
--- a/system/system-versions.md
+++ b/system/system-versions.md
@@ -94,6 +94,7 @@
 | 302 | 1202 | 1.2.0-rc.1    |       Core, Photon, P1, Electron, Xenon, Argon, Boron, X SoM, A SoM, B SoM |
 | 310 | 1210 | 1.2.1-rc.1    |       Core, Photon, P1, Electron, Xenon, Argon, Boron, X SoM, A SoM, B SoM |
 | 311 | 1211 | 1.2.1-rc.2    |       Core, Photon, P1, Electron, Xenon, Argon, Boron, X SoM, A SoM, B SoM |
+| 311 | 1212 | 1.2.1-rc.3    |       Core, Photon, P1, Electron, Xenon, Argon, Boron, X SoM, A SoM, B SoM |
 
 [1] For 0.8.0-rc.1, The v101 bootloader was also released in the Github releases as v200. Thus the next released bootloader in the 0.8.x line should be v201. As of 4/5/2018: 22 device had v200 bootloaders.