I have 15 xlsx files each having multiple worksheets. I want to dynamically loop it in such a way that all the worksheets and workbooks are read inside a single data frame.

I had tried using pd.read\_excel in the following way

```py

filenames = glob.glob("*.xlsx")
dfList=[]
colnames =['dummy','dummy1','dummy2']
for a in filenames:
    df=pd.read_excel(a, sheet_name=None, header = None, encoding = "ISO-8859-1")
    dfList.append(df)

df= pd.concat(dfList, axis=0, ignore_index= True)
df.columns= colnames

```

The error I get when i run the pd.concat is 

```
TypeError: cannot concatenate object of type "<class 'collections.OrderedDict'>"; only pd.Series, pd.DataFrame, and pd.Panel (deprecated) objs are valid

```

and also tried 

```py
for a in filenames:
    df=[pd.read_excel(a, sheet_name=None, header = None, encoding = "ISO-8859-1").values()]
    dfList.append(df)

```

i get the following error

```
TypeError: cannot concatenate object of type "<class 'collections.OrderedDict'>"; only pd.Series, pd.DataFrame, and pd.Panel (deprecated) objs are valid

```