I'm a long time GIS user but new to QGIS. I can convert single raster files in .img format to .tif files in QGIS 3.4.8 without any issues. However, I cannot batch process the same files. The Python error message is:

2019-05-29T16:58:13     WARNING    Traceback (most recent call last):
              File "C:/PROGRA~1/QGIS3~1.4/apps/qgis-ltr/./python/plugins\processing\gui\BatchAlgorithmDialog.py", line 88, in runAlgorithm
              parameters[param.name()] = wrapper.parameterValue()
             AttributeError: 'NoneType' object has no attribute 'parameterValue'

The parameters in the batch file window are the same as in the single file processing window. Can anybody point me to a solution?