Open Bug 1410838 Opened 2 years ago Updated 10 months ago

Error message from capabilities parsing lacks necessary granularity


(Testing :: geckodriver, defect, P3)



(Not tracked)


(Reporter: whimboo, Unassigned)


(Blocks 2 open bugs, )


Currently the following capabilities will result in a failure message which is totally useless:

{"capabilities": {"alwaysMatch": {"moz:firefoxOptions":{"binary":"path"}}}}

The failure as shown is:

1508752193486 webdriver::server DEBUG <- 500 Internal Server Error {"value":{"error":"session not created","message":"Unable to find a matching set of capabilities","stacktrace":"stack backtrace:\n 0: 0x47d2a4 - \n 1: 0x45d174 - \n 2: 0x427701 - \n 3: 0x42ac5a - \n 4: 0x45ff5e - \n 5: 0x45581f - \n 6: 0x4437a6 - \n 7: 0x443aa6 - \n 8: 0x6de879 - \n 9: 0x4439e9 - \n 10: 0x44385b - \n 11: 0x4575c8 - \n 12: 0x6da071 - \n 13: 0x74f38744 - BaseThreadInitThunk\n 14: 0x776a582d - RtlGetAppContainerNamedObjectPath"}}

It should really mention that the binary cannot be found.
> <jgraham> ato: We would change the return type of validation from Bool to Result<(), String> and create a Vec of errors from each capability set we try to match
OS: Unspecified → All
Hardware: Unspecified → All
Version: 57 Branch → Trunk
This issue has actually been original filed as Also see some discussion over there.
Btw. it's not only necessary to check the binary location as given by the capability, but also the path as returned by mozrunner when trying to find the default system installation. If we don't do that we could see issues like
Priority: -- → P3
No longer blocks: 1401129
Blocks: 1466818
No longer blocks: 1441204
No longer blocks: 1466818
No longer blocks: 1491288
Summary: Improve failure message if specified binary cannot be found → Error message from capabilities parsing lacks necessary granularity

This bug was originally filed for, although it talks
only about the specific case of the binary capability not being
valid. In the original issue Simon requested better details in
general for capabilities parsing, so I will repurpose this bug to
change the way we collate errors as I described in

I haven’t decided if this will fix or if I will
address the binary check later.

Blocks: 1524584
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