Received message differs from sent message over serial connection - python-3.x

Question

I am trying to connect two raspberries over a serial connection with pyserial. I wrote two little scripts, for transmitting and receiving. While there is a communication happening between those two, the received message is completely different, than the sent message.
For example if I do
serial1.write(b'hello')
on raspi1, then raspi2 receives:
print(serial2.readline().hex())
fa9b9fff
which is the hex representation of ú›Ÿÿ.
EDIT: Here is the receive and send methods:
sender:
def send_msg(_ser, _msg):
if _ser.isOpen(): # isOpen() is deprecated since version 3.0
try:
_ser.flushInput() # flush input buffer, discarding all its contents
_ser.flushOutput() # flush output buffer, aborting current output 
# and discard all that is in buffer
_ser.write(_msg)
_ser.flush()
except IOError:
print('error communicating...')
else:
print('cannot open serial port')
return
receiver:
def read_line(_ser, _eol_character=b'\n', _timeout=1, _encoding='utf-8'):
buffer = ""
timer = time.time()
while (time.time()-timer)<_timeout:
one_byte = _ser.read(1)
print(one_byte.hex())
if one_byte == _eol_character:
return buffer.encode(_encoding)
else:
buffer += str(one_byte, _encoding, errors='replace')
raise TimeoutError("Timed out while read_line(), make sure there is an EOF!")

Answer 1

The kind of gibberish you're getting indicates three possible causes:
-A mismatch of settings, most likely different baud rates
-Noise on the bus: frequently originating from lacking a common ground reference. This happens when you have not connected only connect the TX and RX signals but leave the GND floating (on desktop computers you'll likely have a common ground even if you don't connect the GND signals because of the safety ground on your house's wiring but on laptops or other battery-powered devices this is a problem and you have to use a third cable to connect GND on both sides of the bus).
-You're trying to communicate using different logic levels. This happens if one side of the bus is working on TTL levels (5V) and the other on 3.3V or when you have a real RS232 level (differential) combined with any of the others. Not to mention if you try to mix RS485 with RS232 or TTL, which, of course, won't work either.