'ascii' codec can't encode character '”' in position 0: ordinal not in range(128)

_Newbie_ issue!

After launching the app via:
`$ PYTHONUTF8=1 adk web --port 8000`
navigating to the browser and entering any text in the _Message_ box on the right pane results in the following response:

```
'ascii' codec can't encode character '”' in position 0: ordinal not in range(128)
```

Tried several basic attempts at resolution, but all failed:

- script declaration:

```
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
```

- environment variable declaration:

```
PYTHONUTF8=1 adk web --port 8000
```

- EXPORT statements:

```
export PYTHONUTF8=1

export LANG=en_US.UTF-8
export LC_ALL=en_US.UTF-8
```

Nothing works, the error message persists. Locale is correctly set to "en_US.UTF-8" as confirmed by **locale** command output.

Any suggestions? Thanks.

Regards.

**P.S.**

```
$ uname -a
Linux BeUlta 6.14.0-15-generic #15-Ubuntu SMP PREEMPT_DYNAMIC Sun Apr 6 15:05:05 UTC 2025 x86_64 GNU/Linux
$ python --version
Python 3.13.7
```