Could not convert string to float: ''

Software Support
1

When I use this module to calculate water purificationIt has never been successful.Always show could not convert string to float:＂I revised the biophysics table again and checked that it was out of control.And I downloaded it in the model.sample dataAfter running, it is still not successful. This is the problem.I don’t know how to do.Uploaded my failed work log and my own biophysics table.Ask the boss for guidance.

Upload the logfile using the :outbox_tray: button

biophysical.csv (328 Bytes)

InVEST-natcap.invest.ndr.ndr-log-2026-05-15–17_34_59.txt (2.4 KB)

2

Hi @Dimple , thank you for posting here. The version of InVEST you are running is quite old at this point. I think it is likely you will be successful if you upgrade to the latest version of InVEST: InVEST Downloads, User Guides, and Data Sources | Natural Capital Alliance

3

InVEST-ndr-log-2026-05-16–00_33_36.txt (2.4 KB)Thank you very much. Under your guidance, I have downloaded the latest version of the Invest model.But I encountered another problem in the operation. It shows proj_identify:Cannot find pro.db.I think I am in the download process, which place is not downloaded, what should I do to make it run successfully, to solve this problem?

4

This new error is interesting. The issue may be related to environment variables on your system. In the InVEST Workbench, can you please do the following:

  1. Go to the “About” menu,
  2. Click “Report a problem”
  3. Click “Find My Logs” and then upload any .log files you have.

These logs may have additional information about environment variables that could be useful to see. Thank you,

5

main.log (144.4 KB)Thanks.This is the logs found by following your instructions.Please help me to see what’s wrong with the system variable environment. Should I add a new variable environment or modify something?

6

@Dimple , thank you for sharing this new logfile. The following environment variables are of interest:

  "PROJ-DB": "D:\\软件\\Invest\\InVEST 3.19.0 Workbench\\resources\\invest\\_internal\\Library\\share\\proj",
  "PROJ-LIB": "D:\\软件\\ABBYY\\InVEST 3.14.2 Workbench\\resources\\invest\\_internal\\proj",
  "PROJ.DB": "D:\\软件\\Invest\\InVEST 3.19.0 Workbench\\resources\\invest\\_internal\\proj",
  "PROJ_DATA": "D:\\软件\\Invest\\InVEST 3.19.0 Workbench\\resources\\invest\\_internal\\proj",

Some of these variables may be interfering with InVEST as it tries to find the proj.db file, causing the RuntimeError: PROJ: proj_identify: Cannot find proj.db. I am not sure how these variables were created on your system. Do you know?

In Windows, you could try searching for “edit the system environment variables” and then if you find these specific Variables, you could delete each one. You should be careful when editing or deleting environment variables, as other software on your computer could also be using them. But in this case, because all the variables reference “InVEST”, I think it is safe to delete them. Then close and re-open the Workbench and try running the model again.

7

Thank you for your reply. These environment variables were created in the system environment variable when I was looking for a solution.But this problem also occurs before these new variables are created.In the system, I removed these variables and the problem still occurred. I don’t know why. Could you give me some advise?

8

@Dimple Thank you for clarifying this. It is best to remove these variables.

I don’t know exactly why the problem still occurs. One thing that could be causing the problem are the non-ASCII (Chinese) characters in the installation path. If possible, you could try installing InVEST to a different location on your computer, such as somewhere on the C:/ drive where there are no non-ASCII characters in the path. Please let us know if that works.