A lot depends on the context, so first, a few questions.

1. Is the site public or internal only?
2. Does the site have members? If yes, can they see additional content when logged in?
3. How many pages of content? Rough guess is fine - 5, 50, 500?
4. Is there Blog or News? If yes, how many articles? 5, 50, 500?
4. Are you keeping the same theme (look & feel)?
5. Are there important modules in use that you will have to replace? (old modules not compatible with DNN 10+)
6. Do you have a solid backup and restore process in place that does not take a lot of time?

Like Jeremy mentioned, there are a lot of factors, and potentially a lot of old modules (extensions).

First you need to decide if you want to upgrade or rebuild.

If you decide to upgrade, my flow is usually:
1. Backup the site files and database (of course)
2. Remove any unused 3rd party extension
3. Upgrade all 3rd party extensions to the latest version that still support the current DNN version.
4. Upgrade one step in https://docs.dnncommunity...rade-path/index.html (make sure to read the requirements section and special notes for some of the versions).
5. Test and decide if that looks stable or not (we are here to help if you get into any issues. Decide if you need to restore or continue.
6. Rinse and repeat with a new backup per step so that you don't get stuck restoring everything when a good point was reached.

If you decide to rebuild, many modules support export/import but not all, so your mileage may vary and it is really a case by case situation on how much work that involves.

Admin notice: I split this off into it's own topic in the upgrading forum

My Site is live for like 20 years, and it does have a lot of modules.

the prod site currently contains telerik modules but in the dev environment i have successfully removed everything and created a cleaner version of it. 

my main concern is about the events module which is heavily customized in the older version.

It's been a very long time since we had any DNN5 websites. However, our usual process for upgrading very old websites is to start fresh and rebuild. With very large websites this can take a lot of work.

Dealing with third party modules and migration of data is specialist work, so it's not for everyone.

Good luck with your upgrade..

DNN 5 -> Current is a very large and complicated upgrade process as the others have already mentioned. You also noted a heavy customization to the Events module which may very well add to your complexity as that module was a heavy user of Telerik depending on the exact version that you are using.

Typically with really old sites we do one of two things.

1. Upgrade the site, following the suggesed upgrade path - https://docs.dnncommunity...s/suggested-upgrade- path/index.html taking backups at each stage. 5.x sites are "fun," but with a lot of care and consideration, you CAN do it. But most likely you are going to have lots of updates to do
2. Start clean, and migrate data that we need from the old systems. This allows for a fresh start, a review of content etc.

I'm a REAL big fan of #2. You may need to manually migrate some of the data, but often times that process is far faster and less risky than doing a huge upgrade.

From my experience, with very old DNN versions I'll start a fresh new install and migrate data (there are so many complex scenarios you can face during the upgrade process specially if you're using third party modules); for all customizations I'll come up with an action plan for each in order to get that migrated over to the new version of the website or find a replacement module that supports the new version of the website.

Another option for customizations will be to use awesome implementations for dynamic content such as 2sxc, OpenContent or Rocket CDS. This will give you a lot of freedom and flexibility since you minimize your third party module dependency. 

Hi Marco,
Thank you for your response.

You are suggesting the migration of the data but in the meantime a lot of the table structure has been changed from 5.6 to latest. how should i deal with that?

Prajjwal are you talking about DNN tables or custom/third party module tables? Since you're doing a big jump from 5.6 to 10.2.2 everything has changed so... a safe step for me will be going page by page and migrate the content itself; on regards to custom/third party module tables before migrating you're going to need a module compatible with the new DNN version of the website and then figure out what information can you move over and which information you can't. For the information that you can't move over I'll recommend you using any of the dynamic content solutions I mentioned before in order for you to replicate that functionality/content.