Upgrading from 2 to 3 and having file write problems

[KenHorse]

#!/usr/bin/python

import serial, time, sys, fileinput
 
#open and configure serial port
ser = serial.Serial(
    port='/dev/ttyUSB0',
    baudrate=19200,
    parity=serial.PARITY_NONE,
    stopbits=serial.STOPBITS_ONE,
    bytesize=serial.EIGHTBITS,
    timeout = .1	
)

#first, clear out buffer
count = 0
while (count < 3):
 count +=1  
 ser.write("\r".encode())

 time.sleep(.1) 

#open file for download
file = open("download.mem", "w+")

#send command to start download
ser.write("1SendEram\r\n".encode())

indata ="" 
Counter = 0
progresscounter = 0
var = 1

while var==1:
  indata = ser.readline()
# print indata
  if indata[0] =="C": #check for first character of "Complete" and exit loop
    break
  if(len(indata) == 0 or indata[0] =="-" or indata[0] == "+" or indata[0] =="T"):
    Counter = Counter + 1	
  else:
    Counter = 0 
    ser.write("\r".encode())
    file.write(indata)
    #LineCount -= 1 
    progresscounter += 1
    progress = progresscounter / 44
    if( progress > 100 ) : progress = 100
    ser.write("OK\r\n")	
	
    print( '\rDownloading: %s (%d%%)' % ("|"*(progress/2), progress)),
    sys.stdout.flush() 
  
  if Counter > 10:
    file.close()
    sys.exit("Unit did not respond. Exiting")
	
print ("\nDownload Complete")  
  
file.close()
sys.exit()

The above code was originally written for Python2.7 and I am upgrading to Python3. I'm slowly working my way down the file (I've corrected various errors as I work my way down) but I'm stuck at the line "file.write(indata)". indata is read from the serial port and I want to write it to the file (download.mem). Python3 throws "TypeError: write() argument must be str, not bytes". This is the file.write statement on line 44

I'm not a total newbie to Python but I kinda am to Python3. I don't see how to cast "indata" as a string so it will write to the file

[Axel_Erfurt]

try

file.write(indata.decode())

[KenHorse]

try

file.write(indata.decode())

Thank you, that worked!