Lab/websites slow (and sometimes fail) loading data (March/Apr 2026)
Dong Ha Seo
12 Mar
Hi,
I am currently trying to launch the jupyterlab but I am getting an error "503 : Service Unavailable". I had the same issue before, and I pressed the 'restart from hub' button and pressed the "Stop my server" button as I did before to solve the issue. But this time, another error message comes up saying my server is not running. Is there an ongoing problem for the entire server or is it just my account that is not working?
I tried launching it again today and it worked this time!
Jasmine Fitzsimons
16 Mar
I have been having a similar issue since about noon EDT today - when initializing loadHalos and loadSubhalos the block of code will run for a very long time and never stops compiling. I have tried restarting the kernel and this does nothing.
Dylan Nelson
17 Mar
Since Feb 23 (2026) the general performance of the Lab when loading simulation data has become less predictable, and is sometimes (but not always) very slow.
We are currently looking into this more.
Pedro Cataldi
9 Apr
Hi Dylan, have there been any updates or possible fixes for this issue? Thanks!
Kate Futrowsky
21 Apr
I am getting this error with the JupyterLab server (and similar ones with other chunks, e.g. 0.1 instead of 0.3.hdf5): trying to load any snapshot data: "Unable to synchronously open object (file read failed: time = Tue Apr 21 21:15:05 2026\n, filename = '/home/tnguser/sims.TNG/TNG100-1/output/snapdir_071/snap_071.3.hdf5', file descriptor = 54, errno = 5, error message = 'Input/output error', buf = 0x5624adda4160, total read size = 512, bytes this sub-read = 512, offset = 418387312)". Is this related to this issue? I also checked the filesystem capacity and it is at 99%; I don't know if this is related either.
Dylan Nelson
21 Apr
Yes as of today (22 April 2026) the filesystem has a problem, and it isn't possible to access the simulation data. Hopefully the computer center will be able to resolve it by tomorrow.
Daeun Jeong
22 Apr
I am having trouble downloading the snapshot 78 data. Some files consistently stop downloading at a specific size. For example, snapshot-78.103.hdf5 always stops at 40 MiB, and the download cannot be resumed afterward. In addition, many chunk files appear to be unavailable, including 0, 61, 62, 103–105, and 358–447.
Do you expect that this issue will also be resolved once the problems mentioned above are fixed?
Dylan Nelson
22 Apr
Yes this is the same issue.
For now, all data downloads/access will return "404 not found" until things are fixed.
Hi,
I am currently trying to launch the jupyterlab but I am getting an error "503 : Service Unavailable". I had the same issue before, and I pressed the 'restart from hub' button and pressed the "Stop my server" button as I did before to solve the issue. But this time, another error message comes up saying my server is not running. Is there an ongoing problem for the entire server or is it just my account that is not working?
Thank you!
I tried launching it again today and it worked this time!
I have been having a similar issue since about noon EDT today - when initializing loadHalos and loadSubhalos the block of code will run for a very long time and never stops compiling. I have tried restarting the kernel and this does nothing.
Since Feb 23 (2026) the general performance of the Lab when loading simulation data has become less predictable, and is sometimes (but not always) very slow.
We are currently looking into this more.
Hi Dylan, have there been any updates or possible fixes for this issue? Thanks!
I am getting this error with the JupyterLab server (and similar ones with other chunks, e.g. 0.1 instead of 0.3.hdf5): trying to load any snapshot data: "Unable to synchronously open object (file read failed: time = Tue Apr 21 21:15:05 2026\n, filename = '/home/tnguser/sims.TNG/TNG100-1/output/snapdir_071/snap_071.3.hdf5', file descriptor = 54, errno = 5, error message = 'Input/output error', buf = 0x5624adda4160, total read size = 512, bytes this sub-read = 512, offset = 418387312)". Is this related to this issue? I also checked the filesystem capacity and it is at 99%; I don't know if this is related either.
Yes as of today (22 April 2026) the filesystem has a problem, and it isn't possible to access the simulation data. Hopefully the computer center will be able to resolve it by tomorrow.
I am having trouble downloading the snapshot 78 data. Some files consistently stop downloading at a specific size. For example, snapshot-78.103.hdf5 always stops at 40 MiB, and the download cannot be resumed afterward. In addition, many chunk files appear to be unavailable, including 0, 61, 62, 103–105, and 358–447.
Do you expect that this issue will also be resolved once the problems mentioned above are fixed?
Yes this is the same issue.
For now, all data downloads/access will return "404 not found" until things are fixed.