My website is developed in magneto 1.5 version. Need to upgrade in new version 1.9 Below are the current asserts on my website:

1. Db size Approx. 9 GB
2. Total Products Approx. 50,000
3. Total Orders 20,000
4. Total customers 23,000

I have followed below steps to achieve this but no luck.

1. Created new instance for the same.
2. Upgraded using Magento connect.
3. Its upgraded successfully version is updated.
4. But when i clear the cache and hit the url its infinite redirect loop.

2nd Approach:

1. Created new instance for the same.
2. Merge the latest version core files and other js, lib etc.. files.
3. Same when i hit the url its infinite loop.

3rd Approach:

1. Created new instance version 1.6
2. And merge the theme and skin files and others that are required to run the theme.
3. Configured the original db instance with this 1.6 version for upgrading the db.
4. Made changes on Db as required.
5. No luck again its loading and loading..

Please suggest. How can i upgrade my store.

Thanks In Advanced !!

My website is developed in magento version 1.5. I Need to upgrade to version 1.9.

Below are the current asserts on my website:

1. Db size Approx. 9 GB
2. Total Products Approx. 50,000
3. Total Orders 20,000
4. Total customers 23,000

I have followed below steps to achieve this but no luck.

1. Created new instance for the same.
2. Upgraded using Magento connect.
3. Its upgraded successfully version is updated.
4. But when i clear the cache and hit the url its infinite redirect loop.

2nd Approach:

1. Created new instance for the same.
2. Merge the latest version core files and other js, lib etc.. files.
3. Same when i hit the url its infinite loop.

3rd Approach:

1. Created new instance version 1.6
2. And merge the theme and skin files and others that are required to run the theme.
3. Configured the original db instance with this 1.6 version for upgrading the db.
4. Made changes on Db as required.
5. No luck again its loading and loading..

Please suggest. How can i upgrade my store?

Thanks In Advance!!