[smartmontools-support] Smartctl: Exception: json.cpp(39): Assertion failed: 'a' <= c && c <= 'z'

[Christian Kujau]

On Mon, 8 Jun 2026, Kevin Prigge wrote:
> I don't have a more current version available, we're using Rocky 8 so
> whatever they ship as standard is what's installed.

That would be material for the Rocky Linux bug tracker then. Except...a 
quick search on the interwebs return quite a few results for this error:

* Exception: json.cpp(39): Assertion failed: 'a' <= c && c <= 'z'
  smartmontools-support/2025-August/001152.html (August 2025)

* Smartctl: Exception: json.cpp(39): Assertion failed: 'a' <= c && c <= 'z'
  smartmontools-support/2024-January/001043.html (Jan 2024)

* Smartctl: Exception: json.cpp(313): Assertion failed: p->type == 
  nt_array when using -l error and json options concurrently
  smartmontools-support/2023-January/000949.html (Jan 2023)

So this looks more and more like some kind of known issue, but I could 
not find anything in the smartmontools issue tracker.

Smartmontools r5022 appears to be RELEASE_7_1 (if I'm reading the SVN log 
correctly), and a lot has changed since then:

 $ git diff --stat RELEASE_7_1.. lib/json.cpp 
 lib/json.cpp | 779 
 1 file changed, 779 insertions(+)

...but only additions, hm. I guess the exception only happens when you use 
the --json option?

C.
-- 
BOFH excuse #71:

The file system is full of it