I\'m probably missing an obvious platform difference that I should be accommodating but I\'m getting this when trying to do a time format (Python2.7)...
I found that I had this problem because MacOS supports "%D" and I had to replace it with "%m/%d/%Y" to make it cross-platform. In general, combining 'simple' format strings like %m seems to be safer than using 'aggregate' strings like %T or %D.