こんにちは or こんにちわ?

How to spell "Konnichiwa"

Do you know how to spell Konnichiwa (hello) in Hiragana?

こんにちは is correct but こんにちわ is increasingly used by young generation mostly by mistake.

Some people intentionally use わ between friends to express a friendly feeling since the Kanji letter "和（わ）" has a meaning "peace and harmony". (*1)

You should know that some people use わ intentionally. But we do not encourage you (foreign students) to do the same. Most people would take it as your mistake.

References

*1 語源由来辞典 - こんにちは