image-upload-example | upload images from the ImagePicker , using a node | File Upload library

Look closely to your rest server side. You've been assigning $imgData value twice which is replacing the value of the decoded base64 to an array value. That is why your code on the line file_put_contents($dir.$imgName, $imgData); unable to get the image that you're trying to save.

You should place your code in this order :

I sorted this out by just uploading the images to s3

I haven't used Expo specifically, but I have setup my RN project to be able to upload to s3. Given the example you posted, it is fairly similar to what I ended up doing.

So obviously the first thing you need to do is go setup a bucket on AWS S3. From within the AWS console you should be able to find your specific access key and access secret, you will need both of those along with your bucket name.

The idea behind the example you posted, and what I ended up doing is to have a controlled server where you can safely use the access key and secret to create a unique "signed" url that can be used to upload the image directly into your bucket. You don't want to do this on your client b/c having a secret on your client is just asking to get hacked. Assume nothing on the client is ever completely secure.

I was already building a node server as the backend to my application so I had this part already up and running. If you are new to creating a backend server, I would suggest looking up how to setup an Express server here. You can host the app for free (with limitations) on a service such as heroku. There is even a great article covering this whole process in a bit more detail here. Basically you create a an app with a distinct GET route that can be hit by your client app. That route will accept a query parameter with the file name of the file that is going to be uploaded. You should use the official aws sdk which will take your access key, secret, bucket name, and the file name then generate a unique url that will be sent back down to your client app.

Essentially what your client app will do is prepare the file needing to be uploaded. You should have the file name of the file ready and then you send a GET request to the url route you just setup on your Express app. When you get a response back from your server it should contain that unique url. I then used react native fetch blob library to perform a PUT request to that unique url you just received. If all goes well it should upload the file directly to that bucket securely. Make sure you set the Content-Type in the header to the type of file you are uploading.

I know this isn't a bunch of code that will do the upload, but it should help you understand what is needed and get you heading in the right direction.