One day, back in the ’80s, all the ATMs at the bank where pilot fish works suddenly refuse to dispense cash. Customers get a cryptic message about the system not being able to process requests.

When fish and his colleagues investigate, they find that the nightly batch job that prepares the files needed by the ATM software had expected to find a specific file on the mainframe that was not there. What happened to it? Ask … the mortgage department?

It seems that, some time ago, the mortgage department had requested a change in the name and format of a file containing interest rates for different types of mortgage loans. Although that change had been in effect for a while, the old, outdated file had never been deleted until someone quite recently did some system maintenance.

And that made a difference to the ATMs why? Fish’s best guess: Someone was sloppy about implementing the JCL script that prepared the files for the ATM software and had simply copy-pasted an irrelevant line into the job. For years, that caused no problem, but when the filename was changed, the ATMs couldn’t get the useless info on interest rates that they somehow “needed.”

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