• [x ] This issue complies with the issue POLICY doc.
• [x ] I have read the documentation at readthedocs and the issue is not addressed there.
• [ x] I have tested that the issue is present in current master branch (aka latest git).
• [x ] I have searched the issue tracker for a similar issue.
• [ N/A] If there is a stack dump, I have decoded it.
• [x ] I have filled out all fields below.

Platform

• Hardware: [ESP-12|]
• Core Version: latest git 31/12/2020
• Development Env: Arduino IDE|
• Operating System: Windows

Settings in IDE

• Module: Generic ESP8266 Module
• Flash Mode: dio
• Flash Size: 4MB/2MB FS
• lwip Variant: v2 Lower Memory
• Reset Method: nodemcu
• Flash Frequency: [40Mhz]
• CPU Frequency: 160MHz
• Upload Using: SERIAL
• Upload Speed: 115200

Problem Description

when using latest git esp core, uploading file to webserver the upload is stuck because curl is waiting an ack that the webserver do not send

C:\Users\luc\Documents\GitHub\ESP3D-WEBUI>curl -v -F "file=@nodemon.json" http://192.168.1.75/upload
*   Trying 192.168.1.75...
* TCP_NODELAY set
* Connected to 192.168.1.75 (192.168.1.75) port 80 (#0)
> POST /upload HTTP/1.1
> Host: 192.168.1.75
> User-Agent: curl/7.55.1
> Accept: */*
> Content-Length: 265
> Expect: 100-continue
> Content-Type: multipart/form-data; boundary=------------------------6509fe3b11f716de
>
* Done waiting for 100-continue

same code using espcore 2.7.4 and older also are working fine and were working as I used it

C:\Users\luc\Documents\GitHub\ESP3D-WEBUI>curl -v -F "file=@nodemon.json" http://192.168.1.75/upload
*   Trying 192.168.1.75...
* TCP_NODELAY set
* Connected to 192.168.1.75 (192.168.1.75) port 80 (#0)
> POST /upload HTTP/1.1
> Host: 192.168.1.75
> User-Agent: curl/7.55.1
> Accept: */*
> Content-Length: 265
> Expect: 100-continue
> Content-Type: multipart/form-data; boundary=------------------------24d01294b659dad6
>
* Done waiting for 100-continue
< HTTP/1.1 200 OK
< Content-Type: text/plain
< Content-Length: 9
< Connection: close
<
ok boomer* Closing connection 0

MCVE Sketch

I use standard API

webserver.on ("/upload", HTTP_ANY, handleMKSUpload, MKSFileupload);

So FSBrowser.ino should do same

That was the last issue from me for 2020 🎆 🎉
Happy new year 2021 🥳 - a big thank you for this year to the dev team and continue your great job ^_^ 🎈