What are synonyms of problem?

Here are some synonyms for "problem," depending on the context and desired nuance:

General:

* Issue

* Difficulty

* Challenge

* Obstacle

* Dilemma

* Quandary

* Predicament

* Trouble

* Crisis

* Complication

*

More formal:

* Conundrum

* Impasse

*

Informal:

* Headache

* Mess

*

Technical:

* Anomaly

* Discrepancy

*

Specific:

* Bug (for a software issue)

* Flaw (for a defect)

*

Negative:

* Burden

* Affliction

*

The best synonym to use depends on the specific situation.