After upgrading to the latest Ionic, latest Capacitor, latest Angular etc on an old app, I eventually got to the point where I was testing the background upload tasks and this error started to arise.
It should be noted I had to include:
implementation 'com.squareup.okhttp3:okhttp:4.10.0'
in my android/app/build.gradle to overcome okhttp issues with this plugin, and then the PendingIntent errors started popping up. The tasks get backgrounded, but never start uploading for real:
D/FileTransferBG: upload with id 852d3a15-d5d8-da8f-ecaf-9442cc42acbe is already exists in upload queue. ignoring re-upload request
Thanks any help is appreciated.