This one?
https://stackoverflow.com/questions/6870824/what-is-the-maximum-length-of-a-filename-in-s3

MinuteGiraffe30 , Hi ! 🙂

What if you try to manually create such a folder?

AgitatedDove14  
Stackoverflow says about the size of the file name, but here the problem is with the size of the folder name. Not sure if the file and folder limits are the same. The error that occurs says that An error occurred (XMinioInvalidObjectName) when calling the CompleteMultipartUpload operation: Object name contains unsupported characters. . At first I thought I was using the wrong characters in the task title, such as backslash, colon or space. But I managed to upload models with the task name including all these symbols when I used fewer override parameters in my hypeparameters optimization task. So I assumed that the problem is in the length of the folder. Here is an example.

Maybe you should make 

naming_function

 as public variable in 

SearchStrategy

 class or allow changing it in 

HyperParameterOptimizer

 class?

I like this idea, let's do that
Just making sure, you hit the 1024 character limit on S3 path?
If this is the case we should also fix the "artifact naming" to take that into account (it already does and has a limit, see here:
https://github.com/allegroai/clearml/blob/24464b7c1019f7a7b3149ecb80a379c5f82337a0/clearml/backend_interface/metrics/events.py#L351
Should we also limit the entire full path?

I run model training for weeks, where I train hundreds of models with different hyperparameters. Therefore, I need automatic naming of newly created tasks. Maybe there are some examples of how to set custom task naming scheme?

Maybe you should make naming_function as public variable in SearchStrategy class or allow changing it in HyperParameterOptimizer class?

Here is an issue https://github.com/allegroai/clearml/issues/516 .

Thanks MinuteGiraffe30 , fix will be pushed later today

Maybe it makes sense to limit or change number of parameters which participate in name generation or allow users to use their own naming scheme. https://github.com/allegroai/clearml/blob/24464b7c1019f7a7b3149ecb80a379c5f82337a0/clearml/automation/optimization.py#L720

I came up with a workaround to solve this problem, but since I run tasks remotely, where not my modified clearml code is used, this problem will remain until you fix it. Should I duplicate this issue in the github?