I get the error Uninitialized string offset when I import users from a file

This usually means you've got bad data inside your import file.

If you're importing using a CSV (Comma delimited file) and your file contains more commas than it should, then you're going to receive errors when importing.

So lets say we have this:

Name, Email, Address
joe, joe@gmail.com, 12 Huntley St NSW Australia
mary, mary@blah.com, 15 Smith St USA
john, john@blah.com, 22 Blah St, Mexico
joanne, 15 Something St Canada

Notice the 3rd line has 4 commas, while the rest are only 3? It should instead look like this:

john, john@blah.com, 22 Blah St Mexico

Also, notice the 4th line has only 1 comma? This should look like this:

joanne,,15 Something St Canada

The quickest way to clean up your CSV is to open it up inside a spreadsheet application such as Microsoft Excel.

Then, search for any commas inside the file and remove them. Notice that Excel will detect your separator commas and make them into columns instead, so only rogue commas that shouldn't be there will be found when you search.

Once you've removed all the commas, then scroll through your file and look for any rows that seem out of line. Remove or fix any that don't fit the exact number of columns that should be there. So in our example above, Joanne's address would have been inside the email column. We need to move that to the address column instead.

Once that's been done, you can now save the file as a CSV file and re-import into the application.