"Cannot read property '_blazorFilesById' of null error" with Blazor InputFile component

Question

I've started getting this error from my Blazor WebAssembly app:

"Cannot read property '_blazorFilesById' of null error" with Blazor app

I'm assuming that's related to the InputFile component I'm using, which has been working fine.

I've tried restarting VS, clean & rebuilding, restarting IIS and killing Chrome all to no avail. What could be causing this?

Answer 1

This turns out to be because I'd added conditional code to hide the InputFile component on the page. Doing that will cause the error as explained in this post on GitHub by BtbN :

Did you modify your page, so the InputFile element is not rendered anymore? It has to stay present, otherwise the browser cleans up any resources associated with it.

Answer 2

I tried keeping the InputFile component inside a Div and conditionally (based on a bool @uploadingInProgress) hiding the Div (esp. during the upload progress) works perfectly

Answer 3

this is happening because you are most likely calling StatehasChanged in the onchange function