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Uploading cfg.json & presets.json via pio's Upload Filesystem Image does not work #5839
Closed as not planned
Description
What happened?
Previously I would flash the filesystem with premade config and presets file in wled00/data in 16.0.0 and this would work well. Now I noticed it has not been working on the most recent nightly source.
To Reproduce Bug
Backup cfg/presets to wled00/data/ and upload via run --target uploadfs --environment esp32c3dev and notice no settings are applied on startup
Expected Behavior
cfg and presets should be applied
Install Method
Self-Compiled
What version of WLED?
Installed version: WLED 17.0.0-devV5 (2607201) "ESP32-C3-QIO"
Which microcontroller/board are you seeing the problem on?
ESP32-C3
Relevant log/trace output
Anything else?
No response
Code of Conduct
- I agree to follow this project's Code of Conduct
Activity
softhack007 commentedon Sep 7, 2026
@UsableLoki8221 uploading "data" is not supported any more since a long time - at least since WLED 0.13.x. WLED generates compressed HTML source files from the content of "data". This folder is not intended for supplying a user-defined
cfg.jsonorpresets.json.Edit:
pio run --target uploadfsis not supported either, because it will most likely generate a SPIFFS filesystem, instead of LittleFS. This explains your observations with WLED 17.0.0-devV5 - the SPIFFS driver was removed in the new framework we use in 17.0.0.softhack007 commentedon Sep 7, 2026
PRs that might be related:
[-]Uploading cfg.json & presets.json via pio's Upload Filesystem Image does not work anymore.[/-][+]Uploading cfg.json & presets.json via pio's Upload Filesystem Image does not work[/+]UsableLoki8221 commentedon Sep 7, 2026
Weird, I was definitely pulling it off in 16.0.0 adequately:
However, in the newest version I just noticed that flashing the filesystem isn't running the "Building FS image from 'wled00\data' directory to .pio\build\esp32c3dev_qio\littlefs.bin" message:
softhack007 commentedon Sep 7, 2026
As I explained - pio filesystem upload is not supported for WLED, even if the feature exists in PlatformIO. Its a "may or may not work" thing.
Edit:
Building FS image from 'wled00\data' directory to .pio\build\esp32c3dev_qio\littlefs.bin...Wrote 983040 bytesmeans that you override the compressed web UI files with a bloated collection of uncompressed files. This can be useful for WebUI debugging, but its definitely not meant for "production".
UsableLoki8221 commentedon Sep 7, 2026
So I flashed WLED 17.0.0-devV5 (2607201) and then used my previous 16.0.0 environment where I copied the contents of wled00/data from 17 into and ran the filesystem and it worked. So I think that something's gotten messed up in the newer environment where pio's filesystem command doesn't catch any files after
Building FS image from 'wled00\data' directory to .pio\build\esp32c3dev_qio\littlefs.binsofthack007 commentedon Sep 7, 2026
@UsableLoki8221 again - you're doing something which is not officially supported, and actually its very much discouraged to create and upload a huge filesystem in the way you explain. I see no need to "fix it", because we never said it would work. Period.
UsableLoki8221 commentedon Sep 7, 2026
@softhack007 How is uploading the filesystem not supported? Its just platformio core functionality that's someone previously configured to upload whatever is in wled00/data from the environment.
Regardless of your impatience I am genuinely trying to point out the discrepancy and be helpful- I figured out why the filesystem uploader stopped working in the latest environment compared to the previous:
previously littleFS (<17.0) used
"mklittlefs" -c wled00\data -s 983040 -p 256 -b 4096 .pio\build\esp32c3dev_qio\littlefs.bin. to build the fs binary.The new littleFS (17.0) uses
build_fs_router([".pio\build\esp32c3dev_qio\littlefs.bin"], ["wled00\data"])which fails to actually make a binary from files in that location.I already wrote myself a script that uses the previous filesystem binary tool so I'm happy- if what I found is helpful then make of that what you will. Period.
softhack007 commentedon Sep 7, 2026
@UsableLoki8221 sorry if I appear impatient. What your proposing is actually a dangerous hack, and I'm obviously struggling to make myself clear on the "why".
a normal WLED build - without FS creation - stores all *htm, *.js, *.css files from wled00/data inside the firmware; files are compressed and inlined into header files. The web server reads these directly from the firmware (read-only), instead of accessing the filesystem.
"uploading the filesystem" creates a huge copy of the same data - in your case, it seems to be ~980Kb, so uploading to a 4MB board may fail due to image size. You might very soon face "out of file space" problems when saving new presets.
the huge copy overwrites everything that is stored inside the firmware. OTA updates may leave you with a broken UI, because firmware and WebUI do not fit together any more
uncompressed files on the filesystem cause userinterface slowdown
overwiting the build-in userinterface by littleFS files can lead to LEDs flickering during file reading, particularly bad on -C3.
All this lead to a design decision (around the time of WLED 0.13.0) of not using filesystem upload (from wled00/data) in WLED. Even when platformIO allows it, WLED builds would become unreliable, 4MB boards will have problems, and OTA updates can lead to a corrupted user interface. Hence the development team consideres it "not supported".
I hope you understood me better now.
UsableLoki8221 commentedon Sep 7, 2026