I have photos on the old iPhoto app and can't access it because I updated my mac

If you upgraded to Catalina, open Photos from the Applications folder or the Dock. If it doesn't automatically import the iPhoto library, relaunch it with the Option key held down, click on Other Library, and choose it.

If you upgraded to Yosemite through Mojave, proceed as above, or put the existing iPhoto application in a location Spotlight doesn't index, log into the Mac App Store with an Apple ID previously used to download it, and get iPhoto 9.6.1 from the Purchases tab.

If you upgraded to Mavericks or earlier, describe exactly what happens when you try to open iPhoto.

(180857)

iPhoto was replaced with Photos several years ago. While you cannot run iPhoto, Photos can convert your library to the new Photos format. Launch Photos with the option key held down. From the dialog, find your iPhoto Library. Photos will create a new library from your iPhoto media. Your iPhoto library will not be changed.

Do you have plenty of space on the drive with the iPhoto Library? While the new Photos library will not require as much room as twice your iPhoto Library because of the hard links, it does require room for previews and the various databases.

Or, it sounds like some of your originals were corrupted. Have you noticed any issues with your iPhoto Library?

Have you tried opening Photos and looking at the new library to see if your images are there?