Be alarmed by DST bug! Why notepad++ sometimes detects fake file changes

When I woke up this morning and looked at my code in Notepad++ the program asked me that all the files were changed by another program, and if I wanted to reload them. But I didn´t change anything, WTF? I was a bit alarmed by this, because when your code is changed and you don´t know how, it´s not a good sign.

Last night, the clock was set back one hour, so I had an extra hour of sleep. With the extra energy of this free sleeping bonus from mother nature, I started to look for the cause of this weird notification.

  • I installed the Notepad++ compare plugin, which hadn´t used so far, and compared the file to a recently backed up version, to see if there were any weird changes… No! Nothing changed in the code, so there should be some other file attribute changed.
  • I looked at the files´ last modified timestamps, but.. No! The were not alle the same, and the dates seemed to correspond with my working hours.
  • So I started to search the internet and… Yes! There seems to be a Daylight Savings Time bug that causes this behaviour. When the clock changes, Windows apparently changes the timestamps of the files by +/- 1 hour, and Notepad detects them as changed.

So ok, it´s no Y2K bug we´re talking about here. But even though it is such a minor bug, it caused me on my Sunday morning to

  • Be alarmed
  • Install and run a new plugin
  • Search the internet for answers
  • Write this blog post

I´m happy to have found a plausible explanation for this behaviour, but I think by now I have lost my extra free DST bonus hour…


Living in Europe as a freelance programmer. Interested in programming in general, web development and machine learning in particular. Currently most used language is PHP, also experienced in JAVA.

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