RIOT-2026.04 "Fire Rizzlease 🫪👍" - Release Notes

View on GitHub The changelog can also be found on GitHub.

RIOT is a multi-threading operating system which enables soft real-time capabilities and comes with support for a range of devices that are typically found in the Internet of Things: 8-bit and 16-bit microcontrollers as well as light-weight 32-bit processors.

RIOT is based on the following design principles: energy-efficiency, soft real-time capabilities, small memory footprint, modularity, and uniform API access, independent of the underlying hardware (with partial POSIX compliance).

RIOT is developed by an international open-source community which is independent of specific vendors (e.g. similarly to the Linux community) and is licensed with a non-viral copyleft license (LGPLv2.1), which allows indirect business models around the free open-source software platform provided by RIOT.

About this release

You can also read the changelog on our guide site.

The 2026.04 release includes:

RIOT is now synced to Codeberg (#21997) 🏔️.
Added support for the pro-micro-nrf52840 (#22089), slstk3301a (#22069) and stm32h7 (#21978) 🤖.
The Guide Site continues to evolve, becoming the default entry point for new users, replacing doxygen. Including more tutorials and an experimental Supported Boards section 👽. The doxygen documentation remains in place for the API and is accessible at https://api.riot-os.org/
Removed over a million lines of vendor code from the EFM32 family, replacing it with a pkg/gecko_sdk dependency (#22040) 🧹.
The Raspberry Pi Pico 2 / RP2350 has been improved so much, you could write a thesis about it, including unified abstractions between RISC-V and ARM and more (#21753) 🐸.
Added drivers for the amg88xx (#22104) and ADS1X1X (#21694) 🚎.

125 pull requests, composed of 229 commits, have been merged since the last release, and 9 issues have been solved. 27 people contributed with code in 84 days. 1878 files have been touched with 25007 (+) insertions and 1141523 deletions (-).

Notations used below

+ means new feature/item
* means modified feature/item
- means removed feature/item

New features and changes

Core

core/compiler_hints.h: improve assume() (#22061)
core/lib/macros: CONCAT with expansion (#22153)

System Libraries

cdc/ecm: add TX timeout (#22116)
sys/event/periodic_callback: add _start_now (#22070)

cdc/ecm: check link status after obtaining out_lock (#22000)
sys/event: fix event thread stack size propagation (#22038)
sys/shell/cmds: improvement of iw scan command (#22051)
sys/usbus: cdc_ecm: handle link up / link down events (#21999)
sys/ztimer64/xtimer_compat: also provide fallback options when ztimer64 is used (#21958)

Networking

gnrc/ipv6/nib: add gnrc_ipv6_nib_dyn_lladdr_get() (#22013)
gnrc/ipv6/nib: make ABR run-time configurable (#21081)
gnrc/ipv6/nib: only add a single link-local address (#22073)
gnrc_pktshark: add new module to pretty-print network traffic (#21284)
sys/shell: add generic udp command (#22049)
sys/string_utils: memxor memrcpy (#22136)

drivers/[s-z]*: change license headers to SPDX format (#22167)
sys/net/gnrc/netif: enable static analysis (#22055)
sys/net/link_layer/ieee802154: split out some header utilities (#22140)

Packages

pkg/qcbor: bump version (#22110)
pkg/u8g2: bump version (#22081)

Boards

boards/pro-micro-nrf52840: add support (#22089)
boards/slstk3301a: add support (#22069)
cpu/stm32: add support for STM32H7 (#21978)
cpu/stm32h7, boards/nucleo-h753zi: add support for more peripherals (#22076)
RP2350: Add RISCV, Unify RP2350, Update UART, Add XH3IRQ Interrupt Controller (#21753)

boards/common/nrf52: include adafruit-nrf52-bootloader dependency early (#22124)
boards/native: use ‘nvm0’ for native fs folder name (#22134)
boards: migrate EFM32-based board config to ztimer (#22099)
sys/walltime: implement alarm functions (#22123)

CPU

cpu/samd5x: support for using ext_osc + xosc + fdpll (#22012)
drivers/ws281x: add SPI backend (#22003)

cpu/efm32: remove i2c clock ‘reset’ (#22077)
cpu/efm32: replace vendor files with the ones from pkg/gecko_sdk (#22040)
cpu/esp32: fix compilation for GCC 15.2 on ESP32x RISC-V SoCs (#22017)
cpu/lpc1768: improve UART driver (#22082)
cpu/rpx0xx: wait for transmission to be completed (#22097)
cpu/sam0_common: update SAML21-based compat headers (#22074)
cpu/stm32: simplify handling of generated IRQ header (#21964)
drivers/ws281x: support rgbw (#21990)
pkg/pkg.mk: enable sparse checkout for non-cache (#22039)

Device Drivers

drivers/amg88xx: add support (#22104)
drivers: add a common driver for ADS1X1X (#21694)

drivers/[a-e]*: Change license headers to SPDX format (#22162)
drivers/[f-h]*: change license headers to SPDX format (#22163)
drivers/[p-r]*: change license headers to SPDX format (#22166)
drivers/slipdev: make default param selection less insane (#22142)
drivers/slipdev: Split out networking/coap into files (#22118)

Documentation

boards/nucleo-h753zi: add pinout to documentation (#22176)
doc/starlight: add unit tests to tutorials (#22042)
doc: add declaration of AI tools (#22169)
doc: Add README & Update Starlight (#22101)
doc: explain use of static analysis (#22127)

doc/starlight: Update to astro v6 (#22145)
doc: Fix riot svg logo color and optimize svgs, also replace png logo with svg logo in guides (#22008)

Build System / Tooling

dist/tools/zsh-completion: add PORT variable (#22060)
make: add enableable sarif output (#22122)
makefiles/arch/native: add debug server config (#22107)

dist/tools/bmp: remove requirements.txt (#22098)
makefiles/tools/openocd-adapters: use non-deprecated ‘adapter serial’ (#22108)
tools/uf2conv: enforce .hex or .elf flashfile format (#22100)

Testing

.github/workflows: do not run workflows on forks (#22085)
ci: sync repo to codeberg (#21997)
gh-actions: deploy guides to main riot-os.org server as well (#21993)
tests/unittests: Update link to flashing guide in README (#22043)
tests: Use common run_check_unittest (#22102)

API Changes

sys/net/nanocoap: use char * as type for char * arguments (#22093)

Uncategorized

CODING_CONVENTIONS: Add reference to Commit Conventions (#22087)
release-notes.txt: add 2026.01 release notes (#22044)

ci/deploy_docs: stop deploying to gh_pages (#22011)

And 12 minor changes.

Deprecations

Deprecations (1)

dist/tools: deprecate git-cache script, embrace git-cache-rs (#22045)

Bug fixes (43)

cpu/efm32: add configurable i2c pull-up (#22065)
cpu/stm32h7,boards/nucleo-h753zi: Add support for periph_vbat, fix ADC bug (#22084)
deploy_docs.yml: add SECURITY.md (#21994)
sys/net/nanocoap: add missing dependency to sock_udp (#22047)
sys/walltime: add automatic test, more backends (#22031)
boards/slstk3402a: expose SPI1 for on-board LCD (#22080)
boards/slstk3701a: fix pin configuration issues (#22068)
build system: handle unsupported make debug* (#22106)
ci/sync: only sync on master pushes (avoid merge queue branches) (#21998)
core/init: don’t call vfs_bind_stdio() in early init (#22170)
cpu/esp8266: Fix crashes of the ESP866 when rebooting with or disconnecting from WiFi (#22014)
cpu/esp8266: fix the crashes on startup in vendor code (#22010)
cpu/native: Fix make all-valgrind (#22046)
cpu/native: fix syscall return values for fwrite() and getpid() (#22144)
dist/tools/usb-cdc-ecm: script fixes (#22001)
doc/CONTRIBUTING.md: fix typo (#22174)
drivers/atwinc15x0: fix a potential buffer overflow on stack (#22041)
drivers/cst816s: Fix touch_dev compatibility (#22141)
drivers/mpu9x50: fix wrong byte-order for gyro and accel reads (#22135)
drivers/netdev_ieee802154_submac: fix do-while loop in ISR (#22002)
examples/basic/filesystem: don’t set main stack size on native (#22132)
gnrc_sixlowpan_frag_sfr: check length before dispatching (#22027)
how_to_doc.md: Spell and wording fixes (#21995)
kw2xrf/Radio HAL: fixed endianness setting of short addressing (#22057)
makefiles/tools: enhance miniterm path finding in serial.inc.mk [backport 2026.04] (#22219)
makefiles/tools: fix esptool installation for riotdocker (#22159)
makefiles: use TZ instead of mounting /etc/localtime for Docker (#22120)
pkg/libsocketcan: fix build on native (#22095)
pkg/lvgl: Fix configuration header and compilation issue (#22005)
pkg/lvgl: Fix LVGL bug when using SDL on native (#22139)
pkg/lwip/sock_udp: correctly report IP family in dual-stack scenario (#22072)
pkg/pkg.mk: Evaluate Sparse Paths for Non-Cache too (#22088)
pkg/pkg.mk: fix sparse checkout initialization (#22113)
si70xx: retry device identification (#22052)
sys/net/gnrc/pktbuf_malloc: fix undefined behavior (#22054)
sys/net/gnrc_sixlowpan: fix a possible NULL ptr dereference (#22066)
sys/net/nanocoap: fix message corruption coap_build_reply() (#22094)
sys/net/nanocoap: fix most pressing API flaws (#22096)
sys/net/nanocoap: make bounds tests more robust (#22048)
sys/net/nanocoap_fileserver: only set payload marker if payload exists (#22133)
sys/suit: check length of URL in suit_worker_trigger() (#22143)
sys/ztimer: fix boolean logic on constant ints (#22131)
tests/unittests: Fix tests with gnrc_pktbuf_malloc + ASAN (#22058)

Known issues

6lo: RIOT does not receive packets from Linux when short_addr is set (#11033)
Address registration handling inappropriate (#15867)
app/netdev: application stops working after receiving frames with assertion or completely without error (#8271)
at86rf2xx: Dead lock when sending while receiving (#8242)
cpu/esp8266: Tracking open problems of esp_wifi netdev driver (#10861)
DHCPv6 client: Handling of NotOnLink incorrect (#20349)
dist/tools/sliptty/start_network.sh: IPv6 connectivity is broken on PC (#14689)
driver/mrf24j40: blocks shell input with auto_init_gnrc_netif (#12943)
drivers/at86rf215: Incorrect channel number set for subGHz (#15906)
DTLS examples cannot send message to localhost (#14315)
Emcute cannot create a double-byte name (#12642)
ethernet: Missing multicast addr assignment (#13493)
ethos: fails to respond to first message. (#11988)
ethos: Unable to handle fragmented IPv6 packets from Linux kernel (#12264)
example/gnrc_border_router cannot answer after some time (#19578)
examples/cord_ep: Dead lock when (re-)registering in callback function (#12884)
examples/gnrc_border_router: esp_wifi crashes on disconnect (#14679)
Forwarding a packet back to its link layer source should not be allowed (#5051)
gcoap example request on tap I/F fails with NIB issue (#8199)
gcoap: Suspected crosstalk between requests (possible NULL call) (#14390)
Global IPv6 addresses remain deprecated after receiving RA (#19846)
gnrc ipv6: multicast packets are not dispatched to the upper layers (#5230)
gnrc/ipv6: “invalid payload length” - corrupted IPv6 header when ENABLE_DEBUG=1 in mbox.c (#20390)
gnrc_border_router stops routing after a while (#16398)
gnrc_border_router: Kconfig and C disagree about number of addresses per interface (#19947)
gnrc_icmpv6_echo: flood-pinging another node leads to leaks in own packet buffer (#12565)
gnrc_ipv6: Multicast is not forwarded if routing node listens to the address (#4527)
gnrc_netif_pktq leaks memory (#17924)
gnrc_rpl: missing bounds checks in _parse_options (#16085)
gnrc_rpl: nib route not updated when topology / DODAG changes (#17327)
gnrc_rpl: takes unusually long time to start routing packets (#19147)
gnrc_sock_udp: Possible Race condition on copy in application buffer (#10389)
gnrc_tcp: gnrc_tcp_recv() never generates -ECONNABORTED (#17896)
ieee802154_submac: IPv6 fragmentation broken (#16998)
LoRaWan node ISR stack overflowed (#14962)
LWIP TCP Communication Error (#19676)
lwip, submac: deadlock on user transmission (#21843)
lwip_sock_tcp / sock_async: received events before calling sock_accept() are lost due to race condition. (#16303)
Missing drop implementations in netdev_driver_t::recv (#10410)
Neighbor Discovery not working after router reboot when using SLAAC (#11038)
netdev_ieee802154: Mismatch between radio ll address and in memory address (#10380)
nrf52: Not able to add global or ULA address to interface (#13280)
nrfmin: communication not possible after multicast ping with no interval (#11405)
ping6 is failing when testing with cc2538dk (#13997)
pkg/lwip: race condition (data loss) in async connection setup (#21874)
pkg/tinydtls: auxiliary data API does not work for async sockets (#16054)
Removing a TNT global address then adding a new one does not work (#20318)
samr30 xpro doesn’t seem to use its radio ok (#12761)
scan-build errors found during 2019.07 testing (#11852)
stale border router does not get replaced (#12210)
test/lwip: enabling both, IPv4 and IPv6, results in unexpected behavior (#18097)
tests/lwip: does not compile for IPv4 on 6LoWPAN-based boards. (#17162)
two nodes livelock sending neighbor solicitations back and forth between each other (#16670)
xbee: setting PAN ID sometimes fails (#10338)

misc issues with tests/trickle (#9052)
periph/timer: timer_set() underflow safety check (tracking issue) (#13072)
periph_timer: systematic proportional error in timer_set (#10545)
saml21 system time vs rtc (#10523)
sys/newlib: gettimeofday() returns time since boot, not current wall time. (#9187)

at86rf2xx: Simultaneous use of different transceiver types is not supported (#4876)
cpu/msp430: GPIO driver doesn’t work properly (#9419)
drivers/at86rf215: not returning RX/IDLE after a while of operation with RPL/UDP (#21685)
drivers/at86rf215: The activation of the address match interrupt is missing in the at86rf215_reset function (#20505)
examples/dtls-wolfssl not working on pba-d-01-kw2x (#13527)
fail to send data to can bus (#12371)
mdt_erase success, but vfs_format resets board (esp32-heltec- lora32-v2) (#14506)
periph/spi: Switching between CPOL=0,1 problems on Kinetis with software CS (#6567)
periph: GPIO drivers are not thread safe (#4866)
PWM: Single-phase initialization creates flicker (#15121)
STM32: SPI clock not returning to idle state and generating additional clock cycles (#11104)
TCP client cannot send read only data (#16541)
tests/periph_flashpage: unexpected behavior on nucleo-l4r5zi (#17599)

examples/micropython: floating point exception while testing on native (#15870)
native not float safe (#495)
native: tlsf: early malloc will lead to a crash (#5796)
VFS_READ show correct data on every SECOND request only (#21470)
ztimer doesn’t wake up on native if the pm_layered module is used (#21083)

Failing tests on FE310 (Hifive1b) (#13086)
boards/hifive1: flashing issue (#13104)
cpu/sam0: flashpage write / read cycle produces different results depending on code layout in flash (#14929)
esp32-wroom-32: tests/netstats_l2 failing sometimes (#14237)
gcoap/esp8266: Stack overflow with gcoap example (#13606)
Interrupt callback function is instantly called on samd51 after setting it from within interrupt callback function (#19861)
MPU doesn’t work on cortex-m0+ (#14822)
newlib-nano: Printf formatting does not work properly for some numeric types (#1891)
periph_timer: Test coverage & broken on STM32F767ZI (#15072)
riscv: ISR stack is too small for ENABLE_DEBUG in core files (#16395)
stm32f7: Large performance difference between stm32f746 and stm32f767 (#14728)

Build dependencies - processing order issues (#9913)
dist/tools/cppcheck/cppchck.sh: errors when running with Cppcheck 1.89 (#12771)
EXTERNAL_MODULE_DIRS silently ignores non-existent entries (#17696)
Kconfig: Unable to set Kconfig boolean variables with default true to false (#21785)
make: ccache leads to differing binaries (#14264)
make: use of immediate value of variables before they have their final value (#8913)
makefiles: make term does not print stderr output of child process. (#21808)

Other issues (77)

[nRF5x] periph_uart unreliable with GCC 9.3.1 (#21842)
[tracking] Bugs found by the peripheral selftest (#20071)
[Tracking] Failures found with testing on real hardware for release (#21882)
[Tracking] Fix failures of test-on-iotlab (#20791)
[TRACKING] sys/shell refactoring. (#12105)
[tracking] unnecessary use of floating point arithmetic (#19614)
_NVIC_SystemReset stuck in infinite loop when calling pm_reboot through shell after flashing with J-Link (#13044)
make term no longer works with JLinkExe v6.94 (#16022)
arduino-nano issue (#22156)
at86rf215 stops receiving until sending a packet (#19653)
b-l072z-lrwan1: tests/ztimer_overhead: test failure (#19224)
backport_pr: Only works for when fork is in user (not in organization) (#18486)
benchmark_udp: hammering with low interval causes issues (#16808)
boards/esp32-wroom-32: tests/mtd_raw flakey (#16130)
Builds fail when different execstack options are around in objects (#18522)
Can’t build relic with benchmarks or tests (#12897)
CC2538-CC2592EM has a very weak transmit power (#17543)
cpp: Exception handling undefined (#17523)
cpu/stm32: fix STM32G4 flash writes failing after motor driver init (#22151)
cpu/stm32: some tests are failing on CM33 (l5, u5) (#17439)
doc/boards: information concerning access to RIOT shell (#17453)
doxygen: CSS hack to hide doc breaks on older browsers (#21312)
edbg: long lines flooded over serial become garbled (#14548)
examples / tests: LoRa tests fail on platforms that don’t support LoRa (#14520)
examples/gcoap: client broken (#19379)
Fixing warnings in RIOT static test (#22216)
flashing issue on frdm-k64f (#15903)
frdm-k22f failing tests/periph_flashpage (#17057)
frdm-k22f fails tests/periph_timer (#19543)
Freeze into semtech_loramac_send call (pkg/semtech-loramac) (#18790)
gcoap: gcoap_req_send and related should return negative for errors (#19393)
gnrc_ipv6_nib: Neighbor Solicitation ping-pong (#18164)
I2C Crashes Kernel on Raspberry Pi Pico (#21187)
ieee802154_security: Nonce is reused after reboot (#16844)
kconfiglib.py choice override of menuconfig bug (#19069)
LVGL tests produce unaligned code, fail to build (#20110)
lwip: drivers/at86rf2xx/at86rf2xx_netdev.c invalid state during TCP disconnect (#17209)
lwip: invalid state transition on ieee802154_submac users (#17208)
Making the newlib thread-safe (#4488)
mcuboot: flashes but no output (#17524)
MTD is confusing (#17663)
openDSME example application does not work reliable out of the box with nRF52840 MDK Dongles (#21922)
Order of auto_init functions (#13541)
periph_rtt: rtt_set_alarm() blocks IRQ for 80 plus usec on STM32 (#19520)
pkg/tinydtls: Multiple issues (#16108)
Potential race condition in compile_and_test_for_board.py (#12621)
RIOT is saw-toothing in energy consumption (even when idling) (#5009)
riotboot: ECC faults (eg. in STM32L5 or STM32WB) not handled gracefully (#17874)
rust-gcoap example is incompatible with littlefs2 (#17817)
Samr30/gpio: Erasing then write mux can generate spurious IRQ (#19993)
samr34-xpro: some tests failing (#19223)
sock_dtls: unable to send big messages (#17996)
spurious IRQs in periph_timer (#18976)
Starlight: “Supported Boards” Known Issues (#22203)
stdio UART input truncated (#21564)
stdio_ethos: infinite shell loop (#17972)
stdio_tinyusb_cdc_acm hangs with picolibc (#19277)
STM32 Nucleo boards improperly clocked (#19778)
STM32F4-discovery + mrf24j40 not working (#19711)
sys/riotboot: documentation issues (#11243)
sys/usb/usbus/cdc/ecm: interface thread blocked when connected host interface is down (#21098)
tests/lwip target board for python test is hardcoded to native (#6533)
tests/periph_flashpage: failing on stm32l475ve (#17280)
tests/pkg/relic is failing on samr21-xpro when built using llvm (#19903)
tests/pkg_libhydrogen: test fails on master for the samr21-xpro with LLVM (#15066)
tests/pkg_libschc: Failing test_reassemble_success_ack_always (#19445)
tests/riotboot does not pass on iotlab-m3 (#22006)
tests/test_tools: test fails while testing on samr21-xpro/iotlab-m3 (#15888)
tests: broken with stdio_rtt if auto_init is disabled (#13120)
tests: some tests don’t work with newlib lock functions. (#12732)
tracking: failing tests with stdio_cdc_acm (#21231)
Types in byteorder.h need a cleanup (#14737)
USB identifiers with funny characters create mojibake (#17776)
usbus/msc: wrong error handling and behavior after usb reset (#19478)
Use of multiple CAN bus on compatible boards (#14801)
ztimer is incompatible with real-time requirements (#18883)
ztimer_periodic: occasional lockups (#21374)

There are 172 known issues in this release

Fixed Issues since the last release (2026.01)

Cannot build examples using the module “sock_tcp” (#22228)
pkg/micropython: test appears to be broken (#22207)
nimble does not compile on nrf52 (#22111)
drivers/mpu9x50: regression (#21663)
rpl, rpble: handle closed connection to parent(s) (#21574)
dist/tools: script falsely accuses headers without C symbols of lacking extern "C" decl (#21394)
[TRACKING] Fixes for automatic tests of ESP32 boards. (#12763)
nrfmin: driver not included in buildtest (anymore) (#12115)
stm32f103xx: I2C has no internal pullups and af config (#10395)

9 fixed issues since last release (2026.01)

Acknowledgements

We would like to thank all companies that provided us with hardware for porting and testing RIOT. Further thanks go to companies and institutions that directly sponsored development time. And finally, big thanks to all of you contributing in so many different ways to make RIOT worthwhile!

More information

http://www.riot-os.org

Discussions

Join the RIOT Matrix room at: #riot-os:matrix.org
Join the RIOT Forum at: forum.riot-os.org
Follow us on Mastodon: floss.social/@RIOT_OS

License

The code developed by the RIOT community is licensed under the GNU Lesser General Public License (LGPL) version 2.1 as published by the Free Software Foundation.
Some external sources and packages are published under a separate license.

All code files contain licensing information.