New I2C hardware timeout errors

My programs were all working for 3 years then suddenly started compilation errors. I created a new sketchbook folder with just my program and a new library folder with just the latest “Heltec_ESP32_Dev-Boards” library. When I try to compile for heltec esp32 wifi lora v2 I get multiple warnings with this error c:\Users\petef\Documents\Newtest\libraries\Heltec_ESP32_Dev-Boards\src\driver\sx1276.c:1289:5: error: implicit declaration of function ‘SpiInOut’; did you mean ‘SpiInit’? [-Wimplicit-function-declaration]
I have to back to version 1.5 to get it to compile. This worked for 3 years until recently when I got these errors in the only partially working Heltic in the Arduino serial port;
“E (118) i2c.master: I2C hardware timeout detected
E (119) i2c.master: s_i2c_synchronous_transaction(924): I2C transaction failed
E (119) i2c.master: i2c_master_multi_buffer_transmit(1186): I2C transaction failed”
This happens over and over and the Heltec doesn’t work at all.

Her is the program:’#include “heltec.h”
byte cntr;
#define BAND 433E6
void setup() {
Heltec.begin(false /DisplayEnable Enable/, true /LoRa Disable/, true /Serial Enable/, true /PABOOST Enable/, BAND /long BAND/);
Heltec.VextON();
Serial.begin(115200);
}
void loop() {
cntr++;
Serial.println(cntr);
delay(1000);
}

I have (almost) exactly the same problem, but for a first compile on a new Cubecell LoraWan V2.
I only received it today and configured teh basic LoraWan example.
At first, it compiled OK, but I could not upload, I got A fatal error occurred: Failed to connect to ESP32: Invalid head of packet (0xF8): Possible serial noise or corruption. I could not find a solution. I tried other LoRaWan Heltec boards, and all of a sudden I got
Arduino\libraries\Heltec_ESP32_Dev-Boards\src\driver\sx1276.c:1289:5: error: implicit declaration of function ‘SpiInOut’; did you mean ‘SpiInit’? [-Wimplicit-function-declaration]
** 1289 | SpiInOut( &SX1276.Spi, addr | 0x80 );**
** | ^~~~~~~~**
** | SpiInit**

I selected the ‘Heltec WiFi LoRa32(V2)’ board in Arduino V2.3.5
I tried to upload the basic ‘blink’ example, but got the same error on serial port. So even when the compilation error has gone, I still am not able to upload. (Tried to reduce upload speed to no success.)

** Update on upload issue: I found this post: CubeCell Board - 'A fatal error occurred: Failed to connect to ESP32: Invalid head of packet'. You have to select the cubecell, so far It is not listed. Will update when resolved. But that does not solve the compile error I guass. **

The CubeCell is not a WiFi LoRa 32 board… completely different hardware… so, at that level, it’s no surprise that you’re having problems. In your case, you need to have loaded the CubeCell hardware support software and select the CubeCell-Board-V2 board.