Getting error when visiting demo app home page

#1

I hope it’s okay to post basic questions like this here?

This is my first look at Yii3 — I have an old Yii1 project that needs rewriting and, as it will probably take me most of next year to complete (working part-time), I’m interested to see if I can skip Yii2 and go with Yii3.

My install seemed to go fine (I followed the instructions at https://github.com/yiisoft/yii-demo) but, when I try to visit the home page, I get:

Yiisoft\Factory\Exceptions\NotFoundException: No definition for Psr\Http\Server\RequestHandlerInterface in D:\Apache24\htdocs\yii3\vendor\yiisoft\proxy\src\ProxyTrait.php:20
Stack trace:
#0 D:\Apache24\htdocs\yii3\vendor\yiisoft\yii-debug\src\Proxy\ContainerInterfaceProxy.php(63): Yiisoft\Yii\Debug\Proxy\ContainerInterfaceProxy->repeatError(Object(Yiisoft\Factory\Exceptions\NotFoundException))
#1 D:\Apache24\htdocs\yii3\public\index.php(51): Yiisoft\Yii\Debug\Proxy\ContainerInterfaceProxy->get(‘Yiisoft\Yii\Web…’)
#2 {main}

I’m sure I’m missing some vital step but I can’t figure it out.

#2

Did you run composer install or such?

#3

Yes, the install seemed to go okay, no errors. It’s been a few days since I posted this question, so I ran composer update again just now, but I still got the same error message.

Then, after reading through the issues in GitHub, I noticed one where rolling back to composer v1 rather than v2 seemed to fix a similar problem, so I tried that and now I have the demo running.

#4

The was a bug in one of the dependency packages when running composer version 2.x. As a temporary workaround try downgrading composer to 1.x

#5

By the way, Yii-3 is not yet released.

Alpha is said to arrive at the beginning of 2021.

#6

I was looking at Yii3 to see how different it is to Yii2 and whether or not I would feel comfortable starting a site re-write in Yii3 once it was relatively stable. After a quick look at Yii3, I’m not sure I “get it” the same way I got Yii1 or Yii2 and, for that reason, and the fact that Yii3 will most likely not be released for many months, I’ll probably stick with Yii2 for now.

#7

Correct decision IMHO, and it will likely be easier to transfer your application from Yii-2 to Yii-3 than from Yii-1.