user66130: I was programming my ATTiny84 when it randomly stopped being able to be programmed.
I have an external 32768 Hz crystal connected to it, and I have been using my Arduino UNO with the ArduinoISP sketch to program it. The following command was working at least once before, but isn't anymore:
C:\Users\Anubhav\Documents\ArduinoData\packages\arduino\tools\avrdude\6.3.0-arduino17/bin/avrdude -CC:\Users\Anubhav\Documents\ArduinoData\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf -v -pattiny84 -cstk500v1 -PCOM3 -b19200 -Uflash:w:C:\Users\Anubhav\AppData\Local\Temp\arduino_build_256583/watch.ino.hex:i -U lfuse:w:0xe6:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m

I tried with -B 5 as well but that didn't seem to help either. The problems seems to be that it's always reading the fuses as 0x000000. This is my output:
avrdude.exe: Version 6.3-20190619
             Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
             Copyright (c) 2007-2014 Joerg Wunsch

             System wide configuration file is "C:\Users\Anubhav\Documents\ArduinoData\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf"

             Using Port                    : COM3
             Using Programmer              : stk500v1
             Overriding Baud Rate          : 19200
             AVR Part                      : ATtiny84
             Chip Erase delay              : 4500 us
             PAGEL                         : P00
             BS2                           : P00
             RESET disposition             : possible i/o
             RETRY pulse                   : SCK
             serial program mode           : yes
             parallel program mode         : yes
             Timeout                       : 200
             StabDelay                     : 100
             CmdexeDelay                   : 25
             SyncLoops                     : 32
             ByteDelay                     : 0
             PollIndex                     : 3
             PollValue                     : 0x53
             Memory Detail                 :

                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               eeprom        65     6     4    0 no        512    4      0  4000  4500 0xff 0xff
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               flash         65     6    32    0 yes      8192   64    128  4500  4500 0xff 0xff
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               lock           0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               lfuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               hfuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               efuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00

             Programmer Type : STK500
             Description     : Atmel STK500 Version 1.x firmware
             Hardware Version: 2
             Firmware Version: 1.18
             Topcard         : Unknown
             Vtarget         : 0.0 V
             Varef           : 0.0 V
             Oscillator      : Off
             SCK period      : 0.1 us

avrdude.exe: PAGEL and BS2 signals not defined in the configuration file for part ATtiny84, using dummy values
avrdude.exe: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.05s

avrdude.exe: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.04s

avrdude.exe: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.04s

avrdude.exe: Device signature = 0x000000
avrdude.exe: Yikes!  Invalid device signature.
             Double check connections and try again, or use -F to override
             this check.


avrdude.exe done.  Thank you.

How do I fix the Yikes!  Invalid device signature. error and why is it occurring?

user23841: As noted in question, the 32kHz crystal is used as a clock source and also at least the first programming was working.
The ArduinoISP sketch has hardcoded ISP clock speed and ISP clock has to be at most 1/4 of MCU speed. So the ArduinoISP sketch SPI_CLOCK has to be set to the much lower value than default 166kHz, which is way too fast for 32kHz MCU clock. The safe value is about 5000 (5kHz)
#define SPI_CLOCK 5000   // (1000000/6)

There is also baud_rate settings for the avrdude, but it's just communication speed between computer and ArduinoISP programmer and changing it won't change SPI_CLOCK (which is ISP clock).

66130: <p>I was programming my ATTiny84 when it randomly stopped being able to be programmed.
I have an external 32768 Hz crystal connected to it, and I have been using my Arduino UNO with the ArduinoISP sketch to program it. The following command was working at least once before, but isn't anymore:</p>

<pre><code>C:\Users\Anubhav\Documents\ArduinoData\packages\arduino\tools\avrdude\6.3.0-arduino17/bin/avrdude -CC:\Users\Anubhav\Documents\ArduinoData\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf -v -pattiny84 -cstk500v1 -PCOM3 -b19200 -Uflash:w:C:\Users\Anubhav\AppData\Local\Temp\arduino_build_256583/watch.ino.hex:i -U lfuse:w:0xe6:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m
</code></pre>

<p>I tried with <code>-B 5</code> as well but that didn't seem to help either. The problems seems to be that it's always reading the fuses as 0x000000. This is my output:</p>

<pre><code>avrdude.exe: Version 6.3-20190619
             Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
             Copyright (c) 2007-2014 Joerg Wunsch

             System wide configuration file is "C:\Users\Anubhav\Documents\ArduinoData\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf"

             Using Port                    : COM3
             Using Programmer              : stk500v1
             Overriding Baud Rate          : 19200
             AVR Part                      : ATtiny84
             Chip Erase delay              : 4500 us
             PAGEL                         : P00
             BS2                           : P00
             RESET disposition             : possible i/o
             RETRY pulse                   : SCK
             serial program mode           : yes
             parallel program mode         : yes
             Timeout                       : 200
             StabDelay                     : 100
             CmdexeDelay                   : 25
             SyncLoops                     : 32
             ByteDelay                     : 0
             PollIndex                     : 3
             PollValue                     : 0x53
             Memory Detail                 :

                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               eeprom        65     6     4    0 no        512    4      0  4000  4500 0xff 0xff
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               flash         65     6    32    0 yes      8192   64    128  4500  4500 0xff 0xff
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               lock           0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               lfuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               hfuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               efuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00

             Programmer Type : STK500
             Description     : Atmel STK500 Version 1.x firmware
             Hardware Version: 2
             Firmware Version: 1.18
             Topcard         : Unknown
             Vtarget         : 0.0 V
             Varef           : 0.0 V
             Oscillator      : Off
             SCK period      : 0.1 us

avrdude.exe: PAGEL and BS2 signals not defined in the configuration file for part ATtiny84, using dummy values
avrdude.exe: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.05s

avrdude.exe: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.04s

avrdude.exe: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.04s

avrdude.exe: Device signature = 0x000000
avrdude.exe: Yikes!  Invalid device signature.
             Double check connections and try again, or use -F to override
             this check.


avrdude.exe done.  Thank you.
</code></pre>

<p>How do I fix the <code>Yikes!  Invalid device signature.</code> error and why is it occurring?</p>
 23841: <p>As noted in question, the 32kHz crystal is used as a clock source and also at least the first programming was working.</p>

<p>The ArduinoISP sketch has hardcoded ISP clock speed and ISP clock has to be at most 1/4 of MCU speed. So the ArduinoISP sketch <code>SPI_CLOCK</code> has to be set to the much lower value than default 166kHz, which is way too fast for 32kHz MCU clock. The safe value is about <code>5000</code> (5kHz)</p>

<pre><code>#define SPI_CLOCK 5000   // (1000000/6)
</code></pre>

<p>There is also baud_rate settings for the avrdude, but it's just communication speed between computer and ArduinoISP programmer and changing it won't change <code>SPI_CLOCK</code> (which is ISP clock).</p>
