# MPPT 150|35 Error 21 after firmware update from v1.59 A058 **URL:** \ **Category:** Q&A and troubleshooting\ **Tags:** venus, mppt\_controllers, domestic, victronconnect, diy\ **Created:** [7 December 2024 01:01 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484 "2024-12-07T01:01:58Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![OiD](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/oid/32/10403_2.png) [@OiD](https://community.victronenergy.com/u/OiD)\ **Post date:** [7 December 2024 01:01 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/1 "2024-12-07T01:01:59Z")
Hello! ![Screenshot_20241206_180953_com.victronenergy.victronconnect](https://europe1.discourse-cdn.com/victron/original/2X/0/041693ac8aa67ad2b5f32f1b1dd6b39288d6ef73.jpeg) Second Victron MPPT suddenly got error 21 current sense issue after updating FW from v1.59 to 1.64 and also after downgrade to 1.61. Does anyone have the 1.59 fw or ideas what happened? Thanks! ---
**Author:** ![ejrossouw](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/ejrossouw/32/1610_2.png) [@ejrossouw](https://community.victronenergy.com/u/ejrossouw)\ **Post date:** [7 December 2024 09:09 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/2 "2024-12-07T09:09:03Z")
Have you looked up the error code [here](https://www.victronenergy.com/live/mppt-error-codes) and resoltion? The code does not auto reset and requires you to disconnect the MPPT as described. ---
**Author:** ![OiD](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/oid/32/10403_2.png) [@OiD](https://community.victronenergy.com/u/OiD)\ **Post date:** [7 December 2024 10:51 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/3 "2024-12-07T10:51:57Z")
Hi! Yes, i have done that multiple times and tried 12 and 24V on the batt side. Device reset to defaults, setting the batt voltage… Powered from the batt side the error takes about 30 seconds to appear. Adding power to the PV input all it does is clear the “Why is the charger off” message until the fault appears. Either the unit got damaged in shipping or the FW update changed something (doubt it) ---
**Author:** ![OiD](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/oid/32/10403_2.png) [@OiD](https://community.victronenergy.com/u/OiD)\ **Post date:** [8 December 2024 15:28 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/4 "2024-12-08T15:28:57Z")
Meh, never mind, I’m sending it back! ---
**Author:** ![francesco](https://avatars.discourse-cdn.com/v4/letter/f/e47c2d/32.png) [@francesco](https://community.victronenergy.com/u/francesco)\ **Post date:** [25 February 2025 10:50 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/5 "2025-02-25T10:50:43Z")
Hi, I have this problem too! Error 21 - current sensor problem Hi, I’m trying to install my bluesolar 150/35. I wired the battery cables correctly first and then the PV, I immediately noticed that the blue LED did not flash with the battery cables connected, then by connecting the PV cables the blue LED turned on steadily and constantly and the app on the smartphone started to “see” the regulator. The screen gave me PV 2.3 w, battery voltage ok and current 0, this morning I received a notification on the app with problem no. 21. What can I do? Thanks to anyone who can help me. Francesco ---
**Author:** ![francesco](https://avatars.discourse-cdn.com/v4/letter/f/e47c2d/32.png) [@francesco](https://community.victronenergy.com/u/francesco)\ **Post date:** [25 February 2025 12:29 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/7 "2025-02-25T12:29:47Z")
hi ludo thanks for the reply, actually in the battery connectors without PV I read the correct battery voltage (25.3) ---
**Author:** ![francesco](https://avatars.discourse-cdn.com/v4/letter/f/e47c2d/32.png) [@francesco](https://community.victronenergy.com/u/francesco)\ **Post date:** [25 February 2025 13:47 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/10 "2025-02-25T13:47:21Z")
Blue Solar ---
**Author:** ![francesco](https://avatars.discourse-cdn.com/v4/letter/f/e47c2d/32.png) [@francesco](https://community.victronenergy.com/u/francesco)\ **Post date:** [25 February 2025 15:22 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/12 "2025-02-25T15:22:45Z")
yes the application only connects when I connect the PV ---
**Author:** ![francesco](https://avatars.discourse-cdn.com/v4/letter/f/e47c2d/32.png) [@francesco](https://community.victronenergy.com/u/francesco)\ **Post date:** [25 February 2025 15:24 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/14 "2025-02-25T15:24:17Z")
[Victron Energy Dongle Smart VE.Direct (Bluetooth)] ---
**Author:** ![francesco](https://avatars.discourse-cdn.com/v4/letter/f/e47c2d/32.png) [@francesco](https://community.victronenergy.com/u/francesco)\ **Post date:** [25 February 2025 15:38 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/16 "2025-02-25T15:38:56Z")
I’ll try now, do you know if the fuse can possibly be replaced? ---
**Author:** ![francesco](https://avatars.discourse-cdn.com/v4/letter/f/e47c2d/32.png) [@francesco](https://community.victronenergy.com/u/francesco)\ **Post date:** [25 February 2025 15:52 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/17 "2025-02-25T15:52:57Z")
sorry but where can I find the factory reset on the victron app? ---
**Author:** ![francesco](https://avatars.discourse-cdn.com/v4/letter/f/e47c2d/32.png) [@francesco](https://community.victronenergy.com/u/francesco)\ **Post date:** [25 February 2025 17:26 UTC](https://community.victronenergy.com/t/mppt-150-35-error-21-after-firmware-update-from-v1-59-a058/14484/20 "2025-02-25T17:26:59Z")
GRAZIE domani mattina provo!