Exception Occurred (..) - 'Microsoft Excel', 'SaveAs ... class failed' - python-3.x

Question

This code basically does what it needs to do. But it does throw an error sometimes whereas I would expect the code to work as all data necessary is present.
So what it does is: (1) Read in users (2) Add information to the Excel dashboard, such as header information, word clouds and profile picture.
Then it saves the Excel file. It sometimes, randomly almost, gives an error: (pywintypes.com_error: (-2147352567, 'Exception occurred.', (0, 'Microsoft Excel', 'Open method of Workbooks class failed', 'xlmain11.chm', 0, -2146827284), None)). What part of the code could cause this?
import os
import xlwings as xw
import pandas as pd
import openpyxl
def get_users(file_name):
"""Read all the users from the csv file."""
users = []
f = open(file_name, 'r')
for line in f:
user = line.strip().split(',')
screen_name = user[0]
users.append(screen_name)
f.close()
return users
def read_csv_file(file_name):
"""Return csv file with accounts."""
data = []
f = open(file_name, 'r')
for line in f:
temp = tuple(line.strip().split(';'))
data.append(temp)
f.close()
return data
def write_panda_to_excel(df, start_cell, wb):
"""Write Pandas DataFrame to Excel."""
sht = wb.sheets['Input']
sht.range(start_cell).value = df
def add_word_cloud(name, cell, wb):
"""Add the WordCloud to Sheet2 """
sht = wb.sheets['Sheet2']
name = os.getcwd() + '\\' + name
rng = sht.range(cell)
sht.pictures.add(name, top=rng.top, left=rng.left, width=325, height=155)
def add_profile_picture(user, cell, wb):
#Add charts to dashboard.
sht = wb.sheets['Sheet1']
picture = [f for f in os.listdir('.') if f.startswith(user + '.')][0]
name = os.getcwd() + '\\' + picture
rng = sht.range(cell)
sht.pictures.add(name, top=rng.top, left=rng.left, width=70, height=90)
app = xw.App(visible=False)
# Read users
os.chdir('../FolderA/')
file_name = 'accounts_file.csv'
users = get_users(file_name)
os.chdir('../Data')
for i, user in enumerate(users):
try:
#count += 1
print(100 * '-')
print(len(users), i+1, user)
# go to directory where the dashboard is stored
os.chdir('../Folder5/FolderE')
wb = xw.Book('Twitter - Individuele Rapportage.xlsm')
os.chdir('../../Data/' + user)
# Remove file if exists
xl = [e for e in os.listdir('.') if e.endswith('.xlsm')]
for e in xl:
os.remove(e)
# add user name to title of Dashboard
sht = wb.sheets['Input_Data']
# add the csv data and profile pictures the other data to the dashboard
df = pd.read_csv(user + '_header_info.csv', sep=',')
write_panda_to_excel(df, 'A1', wb)
cell = 'L20'
try:
add_profile_picture(user, cell, wb)
except:
os.chdir('../../Folder6')
with open('Twitter - Profile picture Error.txt', 'a') as ExceptFile:
ExceptFile.write(str(user) + '\n')
os.chdir('../Data/' + user)
name = user + '_WC.png'
cell = 'Y46'
add_word_cloud(name, cell, wb)
xlname = 'Twitter' + user + '.xlsm'
try:
wb.save(xlname)
wb.close()
except:
os.chdir('../../Folder6')
with open('Twitter - Dashboard Generation Errors.txt', 'a') as myfile:
myfile.write(str(user + "\n"))
myfile.close()
os.chdir('../Data/' + user)
os.chdir('..')
except OSError as exception:
print(exception)
os.chdir('..')
with open('dash_errors.txt', 'w') as dashboard_errors:
dashboard_errors.write(user+"\n")