requests python 500 internal error - python-requests

Question

This is my code the last curl gets a 500 error most of the time, can somebody explain to me why this is happening I'm a newbie here!
headers = {"Accept-Encoding": "gzip, deflate, sdch, br",
"Accept-Language": "en-GB,en-US;q=0.8,en;q=0.6",
"Upgrade-Insecure-Requests": "1",
"User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36",
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"Connection": "keep-alive --compressed"}
url_ = "https://www.apct.gov.in/apportal/index.aspx"
r = requests.get(url_,headers=headers)
#open("/tmp/1.html","w").write(r.content)
c1 = r.cookies
headers = {
'Accept-Language': 'en-GB,en-US;q=0.8,en;q=0.6',
'Upgrade-Insecure-Requests': '1',
'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36',
'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
'Referer': 'https://www.apct.gov.in/apportal/index.html',
'Connection': 'keep-alive --compressed'}
url = "https://www.apct.gov.in/apportal/index.aspx"
r1 = requests.get(url,headers=headers,cookies=c1)
c2 = r1.cookies
# f = open("/tmp/1.html","w+")
# f.write(r.content)
url = "https://www.apct.gov.in/apportal/Search/ViewAPVATdealers.aspx"
time.sleep(2.5)
headers = { 'Accept-Encoding': 'gzip, deflate, sdch, br',
'Accept-Language': 'en-GB,en-US;q=0.8,en;q=0.6',
'Upgrade-Insecure-Requests': '1',
'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36',
'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
'Referer': 'https://www.apct.gov.in/apportal/index.html',
'Connection': 'keep-alive'}
#r = requests.get(url,headers=headers,cookies=c2,timeout=60,verify=True)
Cert ='certifi.old_where()'
r = requests.get('https://www.apct.gov.in/apportal/Search/ViewAPVATdealers.aspx', headers=headers, cookies=c2,verify=certifi.old_where())
r = requests.get('https://www.apct.gov.in/apportal/Search/ViewAPVATdealers.aspx', headers=headers, cookies=c2, timeout=60,verify=True)
soup = BeautifulSoup(r.content)
try:
view_state = soup.find('input', attrs={'id': '__VIEWSTATE'}).get("value")
except:
time.sleep(2.5)
r = requests.get('https://www.apct.gov.in/apportal/Search/ViewAPVATdealers.aspx', headers=headers, cookies=c2, timeout=60,verify=True)
#pdb.set_trace()
# r = requests.get(url,headers=headers,cookies=c2,timeout=60, verify=False)
c3 = r.cookies
soup = BeautifulSoup(r.content)
This is my code above, the last curl is getting a 500 error most of the time - can somebody explain to me why this is happening