Error when executing TIN Interpolation with two sets in QGIS

I am trying to TIN two datasets using TIN Interpolation with XYZ points in QGIS.

I keep getting this error:

Traceback (most recent call last):
File "/usr/share/qgis/python/plugins/processing/algs/qgis/TinInterpolation.py", line 188, in 
processAlgorithm
writer.writeFile(feedback)
Exception: unknown

Execution failed after 135.41 seconds

Loading resulting layers
Algorithm 'TIN interpolation' finished

If I do the sets seperatly, the error only occurs on one of the sets.

What am I doing wrong? I checked the sets and the data is all valid.
If I take the set from a different year, but with the same geographical extent, samen problem.