# Kernel Connection Error for Non-Privileged Users

**URL:** <https://community.wolfram.com/t/kernel-connection-error-for-non-privileged-users/14897>\
**Category:** Questions\
**Tags:** mathematica, external-interfaces, tuning-and-debugging\
**Created:** [October 21, 2019, 1:43pm UTC](https://community.wolfram.com/t/kernel-connection-error-for-non-privileged-users/14897 "2019-10-21T13:43:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![simmsj](https://avatars.discourse-cdn.com/v4/letter/s/df705f/32.png) [@simmsj](https://community.wolfram.com/u/simmsj)\
**Post date:** [October 21, 2019, 1:43pm UTC](https://community.wolfram.com/t/kernel-connection-error-for-non-privileged-users/14897/1 "2019-10-21T13:43:40Z")

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Hello all,

I have an issue with which I hope someone can help me troubleshoot. I installed Mathematica 12 on our Red Hat 7.7 cluster. Initially, everything worked fine; all users could use both the non-GUI (`math`) and GUI front-end versions (`Mathematica`).

At some point, within a couple weeks, something changed, such that now, only the `root` user can launch the GUI front-end. Any other user receives the attached error message, indicating a problem connecting to the kernel. Note that non-privileged users can still successfully launch the non-GUI version without issue. Although I know _something_ must have changed, I cannot think what it would have been; no major updates or changes to the system occurred.

Normally I would attribute this behavior to a permission problem, but for the life of me, I can’t seem to identify it. I have tried re-installing multiple times, and I’ve even `chmod 777` the entire installation directory just to see whether somehow permissions on anything in there could be the problem. I’ve followed all tips on deleting relevant cache and other Wolfram and Mathematica-related directories in user home directories. I simply cannot isolate the underlying issue.

Moreover, this error does not result in a crash, so there is no crash-related information I can examine. I’m able to click the `Quit` button and exit. If I click the close button on the window, it continues processing briefly and then throws the error again, this time continuously, though I can still quit without a true crash.

Any thoughts or guidance as to how I might troubleshoot this further would be welcome.

Warmest regards,

Jason Simms

 ![Serious_Startup_Error.jpg](https://global.discourse-cdn.com/wolfram/original/2X/0/070ed533be4b8391a3fcd901ee56406b637b817c.jpeg)

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**Author:** ![anon21378091](https://avatars.discourse-cdn.com/v4/letter/a/bcef8e/32.png) [@anon21378091](https://community.wolfram.com/u/anon21378091)\
**Post date:** [October 21, 2019, 3:41pm UTC](https://community.wolfram.com/t/kernel-connection-error-for-non-privileged-users/14897/2 "2019-10-21T15:41:49Z")

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Hello,

I managed to solve this issue. I used `lsof` to identify all directories that the kernel was attempting to access, and it turns out it’s trying to read from `/tmp/MathLink`. For whatever reason, this directory was R/W only by root. Once I fixed that, the problem resolved itself.

Jason