I believe that there is a way to increase the debug level, but I don't recall how. Perhaps I am using the wrong terms, but web searches and looking on StackExchange are not providing me anything useful. Basically, I want my *Messages* buffer to output more information about an error. How can I do this?

For example, can I set the debug log level to FINE or something similar?

  • You can trace-function to print some more info about specific function you have in mind, or you could instrument a function for debugging, in which case Emacs will step-debug the function as it being executed, but anything that goes into *Messages* is the result of calling message function, and it doesn't have a verbosity setting, however some particular modes to allow you to control the verbosity of their output, like, for example, flymake-log-level controls how much info it will print. – wvxvw Aug 30 '15 at 23:13

If you set variable debug-on-error to t then Emacs will show you a detailed backtrace of what function calls led to the error. (This affects only actual errors, not non-error messages, which are also logged to *Messages*.)

  • It's worth noting that there's a dedicated interactive command for doing that: M-x toggle-debug-on-error, which will toggle the value of debug-on-error. – wvxvw Aug 31 '15 at 13:18
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    @wvxvw: Yes, definitely worth mentioning. But in terms of telling someone how to turn it on, it can be confusing. People sometimes have it on without knowing it, and toggling then turns it off. The good news is that since debug-on-error is a user option, you can as easily do M-x set-va TAB debug-on-error RET t as you can do M-x toggle-debug-on-error RET. – Drew Aug 31 '15 at 13:24

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