We recently started development with PowerApps (being very new to the product) and built an app that reads, adds, and should write to a SharePoint list. We're running into errors when trying to update an existing list item. It seems similar to these issues (minus the ETAG errors):
We've tried the following solutions:
When trying to update an existing SharePoint list item, will first get this error: "There was a problem saving your changes. The data source may be invalid."
Then this error if you try updating the list again: "An error occurred on the server."
There are three views in this app:
Logic on submit icon:
Could you please share a bit more about your app's configuration?
Do this issue show up only when editing an existing item within your app?
I have made a test on my side and don't have the issue that you mentioned. Please check if you have modified some columns of your SP list on your side.
Please also check if the issue still exists when you create a new item within your SP list. The user @jtillinghast has faced same issue with you, please check the response within the following thread:
Please take a try to re-create an app based on your SP list, and then try it again to check if the issue still exists. If the issue still exists, please take a try to re-create your SP list and create a new app, check if the issue is solved.
In addition, if you want to modify an existing item in your SP list, I think the Patch function could also achieve your needs. More details about Patch function in PowerApps, please check the following article:
Your SharePoint list fields type should be the same type as used in PowerApps fields type. i.e. if using the dropdown in PowerApps, you need to make sure you are using Choice in SharePoint list for the same field.