Unexpected token from request.GetResponse

Unexpected token from request.GetResponse

Hello,
I'm trying to connect to Zoho using v1 authentication.
It worked in february but since march, my program doesn't work anymore. The only thing I changed is my zoho account password.
I regenerated an authtoken multiple times but I have the same error.
My request is https://crm.zoho.com/crm/private/xml/Accounts/getSearchRecords?newFormat=2&authtoken=xxxxx&fromIndex=1&toIndex=200&scope=crmapi&selectColumns=All&searchCondition=(Modified Time|>=|2019-03-26 8:38:38)
And the error is
System.Xml.XmlException: '=' est un jeton inattendu. Le jeton attendu est ';'. Ligne 2, position 2931.
(it means "'=' is an unexpected token")
it occurs on the line "WebResponse response = request.GetResponse();" of my program. 
Do you have any idea?
Thank you