“At that time, there were no fixed processes” regarding how to employ the newly arrived migrants, she said, “but there was such a feeling in the whole of Germany, of integration, integration, ‘Let’s integrate!’”

Mr. Barry has challenged the rejection of his asylum status and is waiting for a decision. For now, he says he will work as long as he can, even though holding a job makes it easier for the authorities to find him if they want to deport him one day.

Susanne Wegele knows that trauma firsthand. In early March, four federal police officers showed up and snapped handcuffs on Ebrima Gassama, also from Gambia, whom she and her husband had trained and employed at their book bindery in Neustadt, in western Germany.

Mr. Gassama, 25, had been working at the company since 2017, although his petition for asylum had also been rejected. He was marched off and driven directly to the airport, leaving behind his stunned colleagues and employers, Ms. Wegele said.

He was one of the more than 26,100 foreigners deported from Germany last year, up from 25,670 in 2017, part of a pledge by the country’s interior minister to ensure that illegal immigrants did not remain.

Ms. Wegele has weekly contact with Mr. Gassama and says she hopes to identify a legal way for him to return to Germany, but for the time being, she has found no one to replace him.

“These are really basic jobs that nobody around here wants to do anymore,” she said. “The government ends up punishing German companies more than the migrants.”