"old" sketch not running with new IDE release

Hi guys.
Today i downloaded the latest versionof the IDE (n. 1.8.1) and used it to compile and upload to my Arduino Uno a sketch I wrote a week ago on an older IDE. The sketch runs a an ethernet server using an ethernet shield and has not been modified since last upload. Now, when i try to connect to it, the web page continues loading, but no html response appears. What should i do?
Thanks

Please post the sketch involved using CODE TAGS ( </> ) so that others may see what you can see.

If somebody else can replicate your issue it could be a bug.
If not then we can take it from there to try understand what to do.
As it stands everyone is flying blind.

The code is pretty simple.
I solved it simply copying the code from the old sketch in a new one, and it does work. Seems like the new IDE is somehow not compatible with projects compiled with older releases (I think I was on 1.6, not sure though).

#include <SPI.h>
#include <Ethernet.h>

byte mac[] = {  
0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(192,168,1,20);
EthernetServer ArduinoServer(80);
char Data_RX;
String msg;
int startingPIN = 6;
int finishPIN = 9;

void setup() {
  Serial.begin(9600);
  Ethernet.begin(mac, ip);
  ArduinoServer.begin();
  Serial.print("server is at ");
  Serial.println(Ethernet.localIP());
  for (int i = startingPIN; i  finishPIN + 1;  i++){
    pinMode(i, OUTPUT);
    digitalWrite(i, HIGH);
  }
}

void loop() {
  msg = ""; 
  isThereCode = 0;  
  EthernetClient client = ArduinoServer.available();
  if (client)
  {
    Serial.println("connected");
    while (client.connected())    {
      if (client.available())      {
        Data_RX = client.read();
        msg += Data_RX;
        if (Data_RX == '\n')
        {
          client.println("HTTP1.1 200 OK");
          client.println("Content-Type text/html");
          client.println("");
          client.println("<!DOCTYPE HTML>");
          client.println("<html>");
          if (/**code contains certain works**/){
              client.print("<p>CONFIRMED</p>);
            } 
          client.print(</html>);
          delay(1);
          break;
        }
      }
    }
    client.stop();
  }
}

Most odd… I dropped it into CREATE and 1.8.1 and it gave me an error.

Can you turn on VERBOSE in preferences and then copy that into here…
It maybe up somebody else’s field of expertise.

"/home/admin/builder/arduino-builder/packages/tools/avr-gcc/4.9.2-atmel3.5.3-arduino2/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -flto -w -x c++ -E -CC -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=10611 -DARDUINO_AVR_UNO -DARDUINO_ARCH_AVR "-I/home/admin/builder/arduino-builder/packages/cores/arduino/avr/cores/arduino" "-I/home/admin/builder/arduino-builder/packages/cores/arduino/avr/variants/standard" "-I/home/admin/builder/arduino-builder/packages/cores/arduino/avr/libraries/SPI/src" "-I/home/admin/builder/arduino-builder/latest/Ethernet-1.1.2/src" "/tmp/168588821/sketch/sketch_feb16b.ino.cpp" -o "/tmp/168588821/preproc/ctags_target_for_gcc_minus_e.cpp"
"/home/admin/builder/arduino-builder/tools/ctags/5.8-arduino11/ctags" -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives "/tmp/168588821/preproc/ctags_target_for_gcc_minus_e.cpp"
Compiling sketch...
"/home/admin/builder/arduino-builder/packages/tools/avr-gcc/4.9.2-atmel3.5.3-arduino2/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD -flto -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=10611 -DARDUINO_AVR_UNO -DARDUINO_ARCH_AVR "-I/home/admin/builder/arduino-builder/packages/cores/arduino/avr/cores/arduino" "-I/home/admin/builder/arduino-builder/packages/cores/arduino/avr/variants/standard" "-I/home/admin/builder/arduino-builder/packages/cores/arduino/avr/libraries/SPI/src" "-I/home/admin/builder/arduino-builder/latest/Ethernet-1.1.2/src" "/tmp/168588821/sketch/sketch_feb16b.ino.cpp" -o "/tmp/168588821/sketch/sketch_feb16b.ino.cpp.o"
Using library SPI at version 1.0 in folder: /home/admin/builder/arduino-builder/packages/cores/arduino/avr/libraries/SPI
Using library Ethernet-1.1.2 at version 1.1.2 in folder: /home/admin/builder/arduino-builder/latest/Ethernet-1.1.2
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:45:15: error: missing terminating " character
client.print("<p>CONFIRMED</p>);
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino: In function 'void setup()':
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:20:32: error: expected ';' before 'finishPIN'
for (int i = startingPIN; i finishPIN + 1; i++){
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:20:45: error: expected ')' before ';' token
for (int i = startingPIN; i finishPIN + 1; i++){
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:20:48: error: 'i' was not declared in this scope
for (int i = startingPIN; i finishPIN + 1; i++){
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino: In function 'void loop()':
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:28:3: error: 'isThereCode' was not declared in this scope
isThereCode = 0; 
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:44:48: error: expected primary-expression before ')' token
if (/**code contains certain works**/){
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:46:13: error: expected primary-expression before '}' token
} 
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:47:24: error: expected primary-expression before '<' token
client.print(</html>);
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:47:25: error: expected primary-expression before '/' token
client.print(</html>);
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:47:26: error: 'html' was not declared in this scope
client.print(</html>);
^
/tmp/326081916/sketch_feb16b/sketch_feb16b.ino:47:31: error: expected primary-expression before ')' token
client.print(</html>);
^
exit status 1

Thats “part” of my error in CREATE with your sketch. (would have been longer but hit the limit…)

Error from 1.8.1 (again trimmed to fit)

Compiling sketch...
"d:\Users\Bob\AppData\Local\Arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\1.20.0-26-gb404fb9-2/bin/xtensa-lx106-elf-g++" -D__ets__ -DICACHE_FLASH -U__STRICT_ANSI__ "-Id:\Users\Bob\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0/tools/sdk/include" "-Id:\Users\Bob\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0/tools/sdk/lwip/include" "-ID:\Users\Bob\Downloads\edruino\Temp/core" -c -Wall -Wextra -Os -g -mlongcalls -mtext-section-literals -fno-exceptions -fno-rtti -falign-functions=4 -std=c++11 -MMD -ffunction-sections -fdata-sections -DF_CPU=80000000L -DLWIP_OPEN_SRC   -DARDUINO=10801 -DARDUINO_ESP8266_ESP01 -DARDUINO_ARCH_ESP8266 -DARDUINO_BOARD="ESP8266_ESP01"  -DESP8266 "-Id:\Users\Bob\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\cores\esp8266" "-Id:\Users\Bob\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\variants\generic" "-Id:\Users\Bob\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\SPI" "-ID:\Sketches\libraries\Ethernet\src" "D:\Users\Bob\Downloads\edruino\Temp\sketch\sketch_feb16a.ino.cpp" -o "D:\Users\Bob\Downloads\edruino\Temp\sketch\sketch_feb16a.ino.cpp.o"
D:\Sketches\sketch_feb16a\sketch_feb16a.ino:45:28: warning: missing terminating " character [enabled by default]

               client.print("<p>CONFIRMED</p>);

                            ^

sketch_feb16a:45: error: missing terminating " character

               client.print("<p>CONFIRMED</p>);

               ^

D:\Sketches\sketch_feb16a\sketch_feb16a.ino: In function 'void setup()':

sketch_feb16a:20: error: expected ';' before 'finishPIN'

   for (int i = startingPIN; i  finishPIN + 1;  i++){

                                ^

D:\Sketches\sketch_feb16a\sketch_feb16a.ino:20:42: warning: for increment expression has no effect [-Wunused-value]

   for (int i = startingPIN; i  finishPIN + 1;  i++){

                                          ^

sketch_feb16a:20: error: expected ')' before ';' token

   for (int i = startingPIN; i  finishPIN + 1;  i++){

                                             ^

sketch_feb16a:20: error: 'i' was not declared in this scope

   for (int i = startingPIN; i  finishPIN + 1;  i++){

                                                ^

sketch_feb16a:20: error: expected ';' before ')' token

   for (int i = startingPIN; i  finishPIN + 1;  i++){

                                                   ^

D:\Sketches\sketch_feb16a\sketch_feb16a.ino: In function 'void loop()':

sketch_feb16a:28: error: 'isThereCode' was not declared in this scope

   isThereCode = 0;  

   ^

sketch_feb16a:44: error: expected primary-expression before ')' token

           if (/**code contains certain works**/){

                                                ^

sketch_feb16a:46: error: expected primary-expression before '}' token

             } 

             ^

sketch_feb16a:46: error: expected ';' before '}' token

sketch_feb16a:47: error: expected primary-expression before '<' token

           client.print(</html>);

                        ^

sketch_feb16a:47: error: expected primary-expression before '/' token

           client.print(</html>);

                         ^

sketch_feb16a:47: error: 'html' was not declared in this scope

           client.print(</html>);

                          ^

sketch_feb16a:47: error: expected primary-expression before ')' token

           client.print(</html>);

                               ^

Multiple libraries were found for "Ethernet.h"
 Used: D:\Sketches\libraries\Ethernet
 Not used: d:\Users\Bob\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\Ethernet
 Not used: D:\Program Files (x86)\Arduino\libraries\Ethernet
Using library SPI at version 1.0 in folder: d:\Users\Bob\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\SPI 
Using library Ethernet at version 1.1.2 in folder: D:\Sketches\libraries\Ethernet 
exit status 1
missing terminating " character

Reading the code you posted i noticed some chars are missing, as in "<p>CONFIRMED</p>

That’s why i copied it into a text editor before posting - my fault.

Anyway what’s happening is weird. Tried opening another file that has been written and compiled in the old IDE, and got same results: it does not work, unless I copy the code in a new sketch: then everything runs smoothly.