Hi @Cla , are all those Excel Writers writing to different sheets on the same .xlsx?
If so you have a “race condition” and the reason why it sometimes works and sometimes doesn’t would then be because sometimes the write operation from one Writer is conflicting with an ongoing operation from another, and other times it has completed ok before the next Writer tries to write.
I’m assuming this is what is happening. If it is, you have a couple of options.
You can run a flow variable flow (red line) from one writer to another thereby ensuring that one completes before another starts. (To show the flow variable ports in KNIME 4.x, right click the node and click “Show Flow Variable Ports”. In KNIME 5.x, simply hover the mouse over the node to make the flow ports visible.)
e.g.
or you can combine them all into the same Excel Writer (click the “…” on an Excel Writer node, to increase the number of sheets it can write to and then run each of your branches into a different input port so that the one Writer is writing all the sheets.
e.g.
If this isn’t your situation, then post back, maybe with a wider view of your workflow, and more details about what is writing to which files… and we can see what else might be the cause.
oh, and welcome to the KNIME community 