nRF52832 Secure DFU: Succeeds at 100% but fails to reconnect (GATT Error 133)

Question

Hardware: nRF52832 (BM832 Module) 
 Programming setup: Custom board connected via Debug Out pins of nRF52-DK (PCA10040) 
 SDK Version: [nRF5_SDK_17.1.0_ddde560] 
 SoftDevice: S132 
 Description: I am implementing Buttonless Secure DFU on a custom nRF52832 module. I recently moved my bootloader start address to 0x71000 to accommodate a larger bootloader size. While the nRF Connect app (Android) shows the DFU transfer reaching 100% and the bootloader seems to "execute" the data object, the reconnect attempt to the application fails with GATT ERROR 133 (0x85) . 
 Observations from nRF Connect Log: 
 
 Jump from Application to Bootloader ( ...EB to ...EC ) works correctly. 
 During the transfer, I occasionally see Error 8 (0x8): GATT INSUF AUTHORIZATION or GATT CONN TIMEOUT , but the nRF Connect app seems to recover and continues the upload. 
 Final Data object executed notification is received. 
 Reconnection attempt to original address ( ...EB ) lasts 10 seconds and ends with Error 133 (0x85) . 
 After the failure, the device is not advertising. 
 
 What I have tried: 
 
 Verified UICR matches the linker FLASH_START . 
 Performed a full chip erase and re-programmed the stack. 
 Verified that the application binary size (approx 96KB) is well within the Dual Bank limits for this layout. 
 
 Questions: 
 
 Could the GATT INSUF AUTHORIZATION error during the transfer be causing a post-update validation issue, even if the transfer reaches 100%? 
 Since I am using a custom BM832 module, are there specific reset or power behaviors after the DFU swap that could lead to a GATT 133 error? 
 Does the S132 require specific RAM adjustments if the bootloader is moved to a lower address like 0x71000?

Fullscreen 
 nRF Connect.txt 
 Download 
 
 nRF Connect, 2026-04-27
Nordic (D9:12:D8:0A:E4:EB)
I	17:48:16.563	[Server] Server started
V	17:48:16.567	Heart Rate (0x180D)
- Heart Rate Measurement [N] (0x2A37)
&#160;&#160;&#160;Client Characteristic Configuration (0x2902)
- Body Sensor Location [R] (0x2A38)
- Heart Rate Control Point [W] (0x2A39)
Unknown Service (0000aaa0-0000-1000-8000-aabbccddeeff)
- Unknown Characteristic [N R] (0000aaa1-0000-1000-8000-aabbccddeeff)
&#160;&#160;&#160;Client Characteristic Configuration (0x2902)
&#160;&#160;&#160;Unknown Descriptor (0000aab0-0000-1000-8000-aabbccddeeff)
&#160;&#160;&#160;Characteristic User Description (0x2901)
&#160;&#160;&#160;Characteristic Presentation Format (0x2904)
- Unknown Characteristic [I W WNR] (0000aaa2-0000-1000-8000-aabbccddeeff)
&#160;&#160;&#160;Client Characteristic Configuration (0x2902)
User Data (0x181C)
- First Name [R W] (0x2A8A)
- Last Name [R W] (0x2A90)
- Gender [R W] (0x2A8C)
V	17:48:16.750	Connecting to D9:12:D8:0A:E4:EB...
D	17:48:16.750	gatt = device.connectGatt(autoConnect = false, TRANSPORT_LE, preferred PHY = LE 1M)
D	17:48:17.319	[Server callback] Connection state changed with status: 0 and new state: CONNECTED (2)
I	17:48:17.319	[Server] Device with address D9:12:D8:0A:E4:EB connected
D	17:48:17.347	[Callback] Connection state changed with status: 0 and new state: CONNECTED (2)
I	17:48:17.347	Connected to D9:12:D8:0A:E4:EB
V	17:48:17.348	Discovering services...
D	17:48:17.348	gatt.discoverServices()
I	17:48:17.584	Connection parameters updated (interval: 7.5ms, latency: 0, timeout: 5000ms)
D	17:48:17.675	[Broadcast] Action received: android.bluetooth.device.action.ACL_CONNECTED
D	17:48:17.758	[Callback] Services discovered with status: 0
I	17:48:17.759	Services discovered
V	17:48:17.770	Generic Access (0x1800)
- Device Name [R W] (0x2A00)
- Appearance [R] (0x2A01)
- Peripheral Preferred Connection Parameters [R] (0x2A04)
- Central Address Resolution [R] (0x2AA6)
Generic Attribute (0x1801)
- Service Changed [I] (0x2A05)
&#160;&#160;&#160;Client Characteristic Configuration (0x2902)
Secure DFU Service (0xFE59)
- Buttonless DFU [I W] (8ec90003-f315-4f60-9fb8-838830daea50)
&#160;&#160;&#160;Client Characteristic Configuration (0x2902)
D	17:48:17.771	gatt.setCharacteristicNotification(00002a05-0000-1000-8000-00805f9b34fb, true)
I	17:48:17.825	Connection parameters updated (interval: 30.0ms, latency: 0, timeout: 5000ms)
I	17:48:22.445	Connection parameters updated (interval: 180.0ms, latency: 0, timeout: 4000ms)
V	17:50:07.206	[DFU] DFU service started
V	17:50:07.206	[DFU] Opening file...
I	17:50:07.213	[DFU] Firmware file opened successfully
V	17:50:07.213	[DFU] Connecting to DFU target...
D	17:50:07.213	[DFU] gatt = device.connectGatt(autoConnect = false, TRANSPORT_LE, preferredPhy = LE_1M | LE_2M)
I	17:50:07.230	[DFU] Connected to D9:12:D8:0A:E4:EB
V	17:50:07.230	[DFU] Discovering services...
D	17:50:07.230	[DFU] gatt.discoverServices()
I	17:50:07.233	[DFU] Services discovered
W	17:50:07.241	[DFU] Application with buttonless update found
V	17:50:07.241	[DFU] Jumping to the DFU Bootloader...
V	17:50:07.241	[DFU] Enabling indications for 8ec90003-f315-4f60-9fb8-838830daea50
D	17:50:07.241	[DFU] gatt.setCharacteristicNotification(8ec90003-f315-4f60-9fb8-838830daea50, true)
D	17:50:07.241	[DFU] gatt.writeDescriptor(00002902-0000-1000-8000-00805f9b34fb, value=0x02-00)
I	17:50:07.580	[DFU] Data written to descr.8ec90003-f315-4f60-9fb8-838830daea50
V	17:50:07.580	[DFU] Notifications enabled for 8ec90003-f315-4f60-9fb8-838830daea50
A	17:50:07.580	[DFU] Indications enabled
V	17:50:07.602	[DFU] Writing to characteristic 8ec90003-f315-4f60-9fb8-838830daea50, value (0x): 01
D	17:50:07.602	[DFU] gatt.writeCharacteristic(8ec90003-f315-4f60-9fb8-838830daea50, value=0x01, WRITE_TYPE_DEFAULT)
A	17:50:07.935	[DFU] Enter bootloader sent (Op Code = 1)
I	17:50:07.936	[DFU] Notification received from 8ec90003-f315-4f60-9fb8-838830daea50, value (0x): 20-01-01
A	17:50:07.936	[DFU] Response received (Op Code = 1, Status = 1)
D	17:50:07.936	[DFU] wait(500)
V	17:50:08.436	[DFU] Disconnecting...
D	17:50:08.444	[DFU] gatt.disconnect()
I	17:50:08.448	[DFU] Disconnected
D	17:50:08.448	[DFU] gatt.refresh() (hidden)
D	17:50:08.451	[DFU] gatt.disconnect()
D	17:50:08.458	[DFU] gatt.close()
V	17:50:08.463	[DFU] Scanning for the DFU Bootloader... (timeout 5000 ms)
I	17:50:08.530	[DFU] DFU Bootloader found with address D9:12:D8:0A:E4:EC
V	17:50:08.540	[DFU] DFU service started
I	17:50:08.540	[DFU] Firmware file opened successfully
V	17:50:08.540	[DFU] Connecting to DFU target...
D	17:50:08.541	[DFU] gatt = device.connectGatt(autoConnect = false, TRANSPORT_LE, preferredPhy = LE_1M | LE_2M)
I	17:50:08.676	[DFU] Connected to D9:12:D8:0A:E4:EC
V	17:50:08.677	[DFU] Discovering services...
D	17:50:08.677	[DFU] gatt.discoverServices()
D	17:50:08.760	[DFU] [Broadcast] Action received: android.bluetooth.device.action.ACL_CONNECTED
I	17:50:09.226	[DFU] Services discovered
V	17:50:09.236	[DFU] Requesting new MTU...
D	17:50:09.236	[DFU] gatt.requestMtu(517)
I	17:50:09.245	[DFU] MTU changed to: 23
V	17:50:09.246	[DFU] Enabling notifications for 8ec90001-f315-4f60-9fb8-838830daea50
D	17:50:09.246	[DFU] gatt.setCharacteristicNotification(8ec90001-f315-4f60-9fb8-838830daea50, true)
D	17:50:09.247	[DFU] gatt.writeDescriptor(00002902-0000-1000-8000-00805f9b34fb, value=0x01-00)
I	17:50:09.264	[DFU] Data written to descr.8ec90001-f315-4f60-9fb8-838830daea50
V	17:50:09.264	[DFU] Notifications enabled for 8ec90001-f315-4f60-9fb8-838830daea50
A	17:50:09.264	[DFU] Notifications enabled
V	17:50:09.265	[DFU] Requesting high connection priority...
D	17:50:09.265	[DFU] gatt.requestConnectionPriority(HIGH)
V	17:50:09.268	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 06-01
D	17:50:09.269	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x06-01, WRITE_TYPE_DEFAULT)
I	17:50:09.281	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:09.311	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-06-01-00-02-00-00-00-00-00-00-00-00-00-00
A	17:50:09.311	[DFU] Command object info received (Max size = 512, Offset = 0, CRC = 00000000)
V	17:50:09.312	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 02-00-00
D	17:50:09.312	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x02-00-00, WRITE_TYPE_DEFAULT)
I	17:50:09.402	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:09.432	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-02-01
A	17:50:09.432	[DFU] Packet Receipt Notif disabled (Op Code = 2, Value = 0)
V	17:50:09.432	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 01-01-8D-00-00-00
D	17:50:09.432	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x01-01-8D-00-00-00, WRITE_TYPE_DEFAULT)
I	17:50:09.491	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:09.491	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-01-01
A	17:50:09.491	[DFU] Command object created
V	17:50:09.491	[DFU] Writing to characteristic 8ec90002-f315-4f60-9fb8-838830daea50 value (0x): 12-8A-01-0A-44-08-01-12-40-08-05-10-34-1A-02-81-02-20-00-28
D	17:50:09.491	[DFU] gatt.writeCharacteristic(8ec90002-f315-4f60-9fb8-838830daea50, value=0x12-8A-01-0A-44-08-01-12-40-08-05-10-34-1A-02-81-02-20-00-28, WRITE_TYPE_NO_RESPONSE)
I	17:50:09.494	[DFU] Data written to 8ec90002-f315-4f60-9fb8-838830daea50
V	17:50:09.495	[DFU] Writing to characteristic 8ec90002-f315-4f60-9fb8-838830daea50 value (0x): 00-30-00-38-98-80-06-42-24-08-03-12-20-ED-22-02-DB-B7-83-5C
D	17:50:09.495	[DFU] gatt.writeCharacteristic(8ec90002-f315-4f60-9fb8-838830daea50, value=0x00-30-00-38-98-80-06-42-24-08-03-12-20-ED-22-02-DB-B7-83-5C, WRITE_TYPE_NO_RESPONSE)
I	17:50:09.498	[DFU] Data written to 8ec90002-f315-4f60-9fb8-838830daea50
V	17:50:09.500	[DFU] Writing to characteristic 8ec90002-f315-4f60-9fb8-838830daea50 value (0x): E1-B8-CE-6C-3B-47-1E-A1-6F-17-EB-87-1C-E7-93-82-D4-99-E5-1D
D	17:50:09.501	[DFU] gatt.writeCharacteristic(8ec90002-f315-4f60-9fb8-838830daea50, value=0xE1-B8-CE-6C-3B-47-1E-A1-6F-17-EB-87-1C-E7-93-82-D4-99-E5-1D, WRITE_TYPE_NO_RESPONSE)
I	17:50:09.503	[DFU] Data written to 8ec90002-f315-4f60-9fb8-838830daea50
V	17:50:09.505	[DFU] Writing to characteristic 8ec90002-f315-4f60-9fb8-838830daea50 value (0x): 3E-32-A5-38-3C-48-00-52-04-08-01-12-00-10-00-1A-40-0E-56-A3
D	17:50:09.505	[DFU] gatt.writeCharacteristic(8ec90002-f315-4f60-9fb8-838830daea50, value=0x3E-32-A5-38-3C-48-00-52-04-08-01-12-00-10-00-1A-40-0E-56-A3, WRITE_TYPE_NO_RESPONSE)
I	17:50:09.509	[DFU] Data written to 8ec90002-f315-4f60-9fb8-838830daea50
V	17:50:09.509	[DFU] Writing to characteristic 8ec90002-f315-4f60-9fb8-838830daea50 value (0x): 15-87-93-DB-4A-FB-D1-3F-27-41-3C-CC-AF-78-19-2E-40-45-F7-11
D	17:50:09.509	[DFU] gatt.writeCharacteristic(8ec90002-f315-4f60-9fb8-838830daea50, value=0x15-87-93-DB-4A-FB-D1-3F-27-41-3C-CC-AF-78-19-2E-40-45-F7-11, WRITE_TYPE_NO_RESPONSE)
I	17:50:09.510	[DFU] Data written to 8ec90002-f315-4f60-9fb8-838830daea50
V	17:50:09.510	[DFU] Writing to characteristic 8ec90002-f315-4f60-9fb8-838830daea50 value (0x): EB-96-01-CB-14-1C-F8-ED-AE-5D-BB-13-F7-75-62-C5-65-17-46-AE
D	17:50:09.510	[DFU] gatt.writeCharacteristic(8ec90002-f315-4f60-9fb8-838830daea50, value=0xEB-96-01-CB-14-1C-F8-ED-AE-5D-BB-13-F7-75-62-C5-65-17-46-AE, WRITE_TYPE_NO_RESPONSE)
I	17:50:09.513	[DFU] Data written to 8ec90002-f315-4f60-9fb8-838830daea50
V	17:50:09.513	[DFU] Writing to characteristic 8ec90002-f315-4f60-9fb8-838830daea50 value (0x): 54-45-7D-45-D5-8F-BF-FD-9D-9E-FE-7B-2D-56-85-B1-26-A4-9D-81
D	17:50:09.513	[DFU] gatt.writeCharacteristic(8ec90002-f315-4f60-9fb8-838830daea50, value=0x54-45-7D-45-D5-8F-BF-FD-9D-9E-FE-7B-2D-56-85-B1-26-A4-9D-81, WRITE_TYPE_NO_RESPONSE)
I	17:50:09.517	[DFU] Data written to 8ec90002-f315-4f60-9fb8-838830daea50
V	17:50:09.517	[DFU] Writing to characteristic 8ec90002-f315-4f60-9fb8-838830daea50 value (0x): 5A
D	17:50:09.517	[DFU] gatt.writeCharacteristic(8ec90002-f315-4f60-9fb8-838830daea50, value=0x5A, WRITE_TYPE_NO_RESPONSE)
I	17:50:09.518	[DFU] Data written to 8ec90002-f315-4f60-9fb8-838830daea50
A	17:50:09.518	[DFU] Command object sent (CRC = 2FD27C1B)
V	17:50:09.518	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 03
D	17:50:09.519	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x03, WRITE_TYPE_DEFAULT)
I	17:50:09.551	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:09.552	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-03-01-8D-00-00-00-1B-7C-D2-2F
A	17:50:09.552	[DFU] Checksum received (Offset = 141, CRC = 2FD27C1B)
V	17:50:09.552	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 04
D	17:50:09.552	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x04, WRITE_TYPE_DEFAULT)
I	17:50:09.596	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:09.596	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-04-01
A	17:50:09.596	[DFU] Command object executed
V	17:50:09.596	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 02-0A-00
D	17:50:09.596	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x02-0A-00, WRITE_TYPE_DEFAULT)
I	17:50:09.626	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:09.626	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-02-01
A	17:50:09.629	[DFU] Packet Receipt Notif Req (Op Code = 2) sent (Value = 10)
V	17:50:09.629	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 06-02
D	17:50:09.629	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x06-02, WRITE_TYPE_DEFAULT)
I	17:50:09.746	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:09.747	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-06-01-00-10-00-00-00-00-00-00-00-00-00-00
A	17:50:09.747	[DFU] Data object info received (Max size = 4096, Offset = 0, CRC = 00000000)
V	17:50:09.762	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 01-02-00-10-00-00
D	17:50:09.762	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x01-02-00-10-00-00, WRITE_TYPE_DEFAULT)
I	17:50:09.776	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:09.777	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-01-01
A	17:50:09.777	[DFU] Data object created
A	17:50:42.436	[DFU] Uploading firmware...
V	17:50:42.436	[DFU] Sending firmware to characteristic 8ec90002-f315-4f60-9fb8-838830daea50...
V	17:50:42.470	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 03
D	17:50:42.470	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x03, WRITE_TYPE_DEFAULT)
I	17:50:42.585	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:42.586	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-03-01-18-80-01-00-60-A7-26-8B
A	17:50:42.586	[DFU] Checksum received (Offset = 98328, CRC = 8B26A760)
V	17:50:42.587	[DFU] Writing to characteristic 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 04
D	17:50:42.587	[DFU] gatt.writeCharacteristic(8ec90001-f315-4f60-9fb8-838830daea50, value=0x04, WRITE_TYPE_DEFAULT)
I	17:50:42.615	[DFU] Data written to 8ec90001-f315-4f60-9fb8-838830daea50
I	17:50:42.959	[DFU] Notification received from 8ec90001-f315-4f60-9fb8-838830daea50, value (0x): 60-04-01
A	17:50:42.959	[DFU] Data object executed
A	17:50:42.960	[DFU] Upload completed in 33208 ms
I	17:50:43.137	[DFU] Disconnected by the remote device
D	17:50:43.138	[DFU] gatt.refresh() (hidden)
D	17:50:43.144	[DFU] gatt.disconnect()
D	17:50:43.155	[DFU] gatt.close()
D	17:50:43.203	gatt.close()
D	17:50:43.207	wait(200)
V	17:50:43.407	Connecting to D9:12:D8:0A:E4:EB...
D	17:50:43.408	gatt = device.connectGatt(autoConnect = false, TRANSPORT_LE, preferred PHY = LE 1M)
D	17:50:53.439	[Server callback] Connection state changed with status: 0 and new state: DISCONNECTED (0)
I	17:50:53.439	[Server] Device disconnected
D	17:50:53.444	[Callback] Connection state changed with status: 133 and new state: DISCONNECTED (0)
E	17:50:53.444	Error 133 (0x85): GATT ERROR
I	17:50:53.444	Disconnected